Unleavened Heaven: Matzah Tiramisu Cake

This year, I wasn’t able to host or attend a Passover Seder, so I wasn’t planning on baking for Passover. I was content scrolling through loads of Instagram food porn including flourless chocolate cakes, coconut macaroons, and various nut-based treats (all of which are leaps and bounds more appetizing than the Passover “cake” mixes and rubber jelly fruit slices peddled by the likes of Manischewitz). If you are not familiar with the delicacy that is matzah, it is a flat, unleavened “bread” eaten during the Jewish holiday of Passover to symbolize the unrisen bread that the Hebrew slaves hurriedly took with them as they left Egypt after Moses liberated them from the Pharoah– as the story goes. Jews who observe Passover do not eat foods made with flour, grains, or leaveners for the 8-day duration of the holiday, so we have to get creative in the dessert department to keep that sweet tooth satiated. (Hey, 8 days is a LONG time without cake.) I have not actually observed the deprivation part of the holiday for several years; instead, I prefer to supplement my regular diet with my favorite nostalgic Passover foods, but I don’t stress too much about avoiding flour anymore. Modern matzah tastes something like cardboard in my opinion, and frankly, I avoid eating it on its own as much as possible during Passover. In other words, I will slather it with cheese or peanut butter, or better yet, I love to fry it up with egg to make Matzo Brei— anything that makes it not taste like matzah!

So as I said, I wasn’t really baking this year… but then I almost dropped my phone when I saw Robicelli’s Tiramatzu in my Instagram feed. ARE. YOU. KIDDING. ME. They created a behemoth tiramisu layered with matzah (instead of ladyfingers—f*cking brilliant, people!), mascarpone mousse, and espresso ganache. I had never seen anything like it; Robicelli’s comes up with some bat-shit crazy/awesome desserts sometimes—I mean, have you seen their Nutellasagna?? I have been on a recent tiramisu blitz (see here and here), and I was going to take a break to work on other baking projects, but when I saw that 4-layer tiramisu tower THAT I CAN’T HAVE BECAUSE I’M NOT IN BROOKLYN, I knew I had to make my own version. Best application of matzah EVER! By the way, I would totally not mind some tips from Allison Robicelli. How did you get the cake so high? How did you get the matzah to be awesomely wavy? How does your mascarpone look so fluffy? Any chance you’re reading this?? So.many.questions.

I mean, seriously. (© Robicelli’s)

I found a perfect (and super simple) espresso- and Kahlúa-laced ganache from Food & Wine, but the mascarpone proved to be a lot more challenging, and I ended up cobbling together a recipe after several hours of research. In a regular tiramisu, you generally make a mascarpone cream, which tends to stay, well, creamy; this is fine because it is contained in a dish. To make a tiramisu cake, on the other hand, you need the mascarpone to be stiff enough to stand on its own on a plate. One way to achieve this is to make a mousse, which contains gelatin. I’m not sure if gelatin is what Robicelli’s used, but that’s my guess. (UPDATE 4/19/15: Robicelli’s kindly responded to my questions over Twitter. They did not in fact make a mousse, but rather a semifreddo. I may have to re-work this next year with semifreddo because OMG.) The gelatin firms up the mascarpone cream to a fluffy, yet sturdy, consistency so that it has enough structure to stand independently. My previous experience with gelatin/mousse consists of a failed pumpkin mousse cake several years ago when I was a much less experienced baker, so I was a bit apprehensive; however, I’m always curious about new techniques and ingredients, so I decided to give it a whirl. In fact, over my Spring Break I made two gelatin recipes, and I learned waaaay more about gelatin than I thought I’d ever want to know! (What I would like to NOT talk about is where gelatin comes from, which is why I am NOT going to belabor the point that gelatin is usually made from animal collagen. Yep, we’re done NOT talking about it.) Incidentally, gelatin is not kosher, so if you want to make this actually kosher for Passover, you can substitute agar agar, a vegetarian gelling agent. I know nothing about using it, but these people seem to. (UPDATE 4/14/17: I was finally to experiment with a different mousse filling this year. It did not turn out to be a semifreddo, but it’s much easier than messing with gelatin. Head over here and check out the new and improved recipe.)

Gelatin comes in powdered/granulated form, or in sheets that look like thin, transparent plastic. Professional pastry chefs often prefer gelatin sheets, so I wanted to get familiar with those (plus I’d bought some years ago and hadn’t used them yet). Sheets are odorless and easy to use (no messy granules to measure), they make a clearer gel, and there’s no chance of undissolved granules. Gelatin must be softened (known as “bloomed”) in water before melting it, regardless of which form you use. This I knew; what I didn’t know was that the term ‘bloom’ also has another meaning in the gelatin world. Gelatin is available in different strengths, measured in grades of bloom; the higher the bloom grade, the stronger/stiffer the gelatin. (Sheets come in Bronze/Silver/Gold/Platinum grades, spanning a range of about 125-265 bloom, with Bronze sheets being the weakest and Platinum, the strongest.) The most commonly used are Silver and Gold grades– in this recipe I used Gold. Knox‘s granulated gelatin (one of the most common brands) has a bloom strength of 225, which is similar to the Gold range.

I found a number of great resources about gelatin, and these people know a hell of a lot more than I do, so have at it:

• David Lebovitz (practical facts and tips)
• Modernist Pastry (scroll to the middle of the page)
• Stella Culinary (info on gelatin sheets and bloom strength)
• Chef Steps (science of gelatin and a lot of math that I can’t wrap my head around)

Some of the major takeaways for beginners working with gelatin include:

• Bloom the gelatin in COLD water. Hot water will not soften the gelatin properly.
• After softening the gelatin, it must be melted/dissolved before incorporating into other ingredients.
• Do not boil liquid with gelatin in it, as it will prevent the gelatin from setting.
• Converting between powder and sheets can be tricky, and there isn’t an exact conversion formula due to the variation in brands and bloom strength. However, a *somewhat* decent rule of thumb is: 1 envelope granulated gelatin = 1 tablespoon powdered gelatin = 3 Gold gelatin sheets… give or take.

I’m going to focus on working with gelatin sheets hereafter in this post– I highly recommend them, regardless of your experience level with gelatin. You can find them in restaurant/baking supply stores, on Amazon, and at Pastry Chef Central, just to name a few. Gelatin sheets must be bloomed in water for 5 minutes and are usually dissolved in a warm liquid that is then added to the rest of the mousse ingredients. If there isn’t a warm liquid in the recipe in which to dissolve the gelatin (such as in this recipe), you can carefully melt it by itself and add it directly to the cold ingredients in the mousse, BUT make sure to add it while moving around the ingredients. If the gelatin hits the cold ingredients and sits, it will quickly turn into glue-like clumps.

To build this cake, I needed some kind of structure to contain the layers so they could set. I purchased a stainless steel 7” square cake mold, which I lined with acetate. This was a little tricky because it’s hard to get the acetate into the corners, but a little masking tape did the trick. You’ll then assemble the layers inside the tall square, and chill the whole thing like this; when it’s set, you remove both the square mold and the acetate, and you should have a free-standing tiramisu cake! If you have some other vessel with a removable mold (small square springform pan perhaps?), that would probably work as well, though I do recommend lining it with acetate for easy unmolding. If you do not own such a vessel/mold, it’s possible that this would work free-form. The mousse is pretty thick, so I think it would hold together once it chills, though it would look more “rustic” (read = messy).

Now, you might be asking, “Lady, aren’t you a little late posting this for the holiday again?” (See here and here… *sigh*) That may be true; but if you’re anything like me, you have some leftover matzah! And also, even if you do like eating matzah on its own (not like me), you might be pretty damn sick of it by now. So I say, make it dessert! 🙂

Matzah Tiramisu Cake
Inspired by Robicelli’s Tiramatzu
Yields 12-16 servings

You can make this “cake” as many layers as you want, and you can adjust the thickness of the mousse layers. I went with 5 layers, but you can certainly stack more or fewer, and adjust your quantities of mascarpone and ganache accordingly. Since I wasn’t trying to feed a bakery full of people, I made my layers fairly thin, but if you want a taller tiramisu, feel free to double the mascarpone for thicker layers, like the glorious monstrosity above.

I made the ganache in 2 batches– one for the 4 layers inside the tiramisu, and one for the top layer, which goes on gooey after the whole thing has chilled. This way, it can drip over the sides, like the unabashed food porn that is Robicelli’s photo. Alternatively, you can make all the ganache at the same time and finish the tiramisu with ganache on top (add together the quantities for both batches), but that top layer will of course solidify in the fridge with the other layers, and won’t look all sexy. Important life decisions to make here.

For espresso ganache batch #1 (adapted from Food & Wine):

• 15 ounces good-quality bittersweet chocolate, chopped
• 1 ½ cup + 1 tablespoon heavy whipping cream
• 1 ¼ teaspoons instant espresso powder
• 4 teaspoons Kahlúa liqueur

For mascarpone mousse:

• 3 Gold gelatin sheets + enough water to cover them in a bowl
• 1 pound mascarpone cheese
• 1 cup confectioners’ sugar
• 2 cups heavy whipping cream
• 1 tablespoon vanilla bean paste or vanilla extract

For espresso ganache batch #2:

• 6 ounces good-quality bittersweet chocolate, chopped
• ½ cup + 2 tablespoons heavy whipping cream
• ½ teaspoon instant espresso powder
• 1 ½ teaspoon Kahlúa liqueur

For tiramisu assembly:

• 10 ounces cooled espresso or strong coffee, or cold brew coffee (I used Stumptown Cold Brew)
• 5 matzahs (7″ squares), or the number of your choice

Prepare the cake mold:
Line a quarter-sheet pan or small platter with parchment paper. Line the interior of a 7″ square cake mold with acetate that is about 4″ high. Try to push it into the corners as much as possible; tape it to the metal from the outside all the way around, and secure the ends of the acetate to each other on the outside of the acetate (between the acetate and the metal– like I said, a little tricky). Do not tape the acetate to the inside of the metal square— you will not be able to remove the cake with its acetate wrapper when unmolding the tiramisu. Place the prepared square on the lined pan and set aside.

Make Batch #1 of ganache:
Place the chocolate in a heatproof bowl. Heat the cream in a small saucepan just until it starts to boil. Remove the pan from the heat. Whisk in the espresso powder until it has dissolved. Slowly pour the hot cream over the chocolate and let it stand for 1-2 minutes. Gently whisk the chocolate until it is melted, smooth, and homogenous, starting in the center and working your way outward. Add the Kahlúa and whisk until incorporated. Let the ganache cool to room temperature or until thickened enough to spread. Set aside.

Make mascarpone mousse:
Submerge the gelatin sheets in water in a medium bowl, making sure the entire strips are in the water. (Fold them over if needed.) Let the sheets bloom for 5 minutes. Once completely softened, they will feel quite jelly-like in your hand– handle very gently. Remove the sheets from the water and gently squeeze out the excess water. Place the crumpled up gelatin sheets in a small bowl and microwave *just* until melted, about 5-7 seconds on medium power. (I found that they were on the verge of boiling after 10 seconds and had to start over– melting gelatin without a liquid is extremely delicate.) Set aside.

Meanwhile, place the mascarpone cheese in the bowl of a stand mixer fitted with the paddle attachment and beat on medium-low speed to loosen it. Add the confectioners’ sugar and beat on medium-low until completely incorporated. Scrape down the sides and bottom of the bowl and mix for a few more seconds.

With the mixer going on low speed, slowly pour/scrape the melted gelatin into the mascarpone. Try to pour it between the side of the bowl and the paddle to avoid it splashing all over the sides of the bowl. Scrape the bowl and mix again to incorporate any unmixed ingredients.

Replace the mixer paddle with the whisk attachment. Gradually add the cream while the mixer is running on medium-low speed. Once all the cream has been added and the mixture starts to thicken, turn up the mixer to medium-high and beat until medium peaks form. Add the vanilla paste or extract and beat until blended.

Assemble tiramisu:
Retrieve the prepared cake mold and pan/platter. Pour the coffee into a shallow vessel with enough room to lay the matzahs flat; I used a rimmed quarter-sheet pan. Soak 1 matzah on both sides for several seconds on each side– these should be well-soaked (unlike traditional ladyfingers, which get soggy). Let the excess coffee drip back into the pan.

Place the matzah into the bottom of the acetate-lined square. Scoop about 1 ½ cups mascarpone mousse onto the matzah and spread it in an even layer to the edges of the square all the way around. The bottom layers are a bit awkward to smooth out because it’s hard to jam an offset spatula in there, but it doesn’t have to be perfect. Pour about ½ cup ganache on top of the mousse and spread it in an even layer. Repeat with 3 more layers of matzah, mascarpone, and ganache. (You should have used up all the ganache at this point.) Add 1 more layer each of matzah and mascarpone– the very top should be mascarpone for now; smooth the mousse out evenly. Try to cover carefully with plastic wrap if you can– Glad Press n’ Seal Wrap works well here because it can grip the acetate and metal mold. Chill in the fridge overnight.

Make Batch #2 of ganache:
When the tiramisu has firmed up, you can go ahead with the top layer of ganache. Repeat the same steps as above. Allow it to cool and thicken slightly, but not too much– when the warm ganache hits the cold tiramisu, it will firm up quickly, and you want it thin enough to drip all sexy down the sides.

Have ready whatever platter on which you plan to serve the tiramisu. Remove the tiramisu from the fridge. Make sure you have a legitimately solid block. Pick up the whole thing and peel the parchment from the bottom. Transfer the tiramisu (still in the mold) to the platter. Remove the tape pieces from around the mold. Carefully, but firmly, remove the square mold from around the acetate. This part is tricky, because it may be difficult to pull the mold up and over the acetate. Take it slowly and gradually, wiggling it as needed to loosen it. If you have someone else nearby to help you, pick up the tiramisu block from the bottom and have the other person pull the mold down. Either way, get it off!

Detach the tape holding the acetate together and peel it from around the tiramisu. Your “cake” should now be a free-standing matzah tower.

Pour the ganache over the top of the tiramisu, allowing it to drip slowly over the edges. Use an offset spatula to coax the ganache to the edges if needed. What I ended up doing was pouring about half of the chocolate in a thin layer, which didn’t drip much, just covering the top. I then cut the tiramisu in half and poured the rest of the ganache over each half for maximum over-the-side drippage.

Allow the ganache to set for 15-20 minutes in the fridge. Cut into slices and serve immediately.

© Dafna Adler & Stellina Sweets, 2015.