At the End of the Rainbow: Irish Chocolate Biscuit Cake

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Happy St. Patrick’s Day! Let me start this Irish-inspired post by saying that… I love American pastry. I believe that, for all the beautiful desserts in the world, no one makes a layer cake or a thick, chewy cookie like American bakers. But… what if I told you that there is something we are sorely missing out on? Something that no American chocolate-eater should ever live without? I don’t know about you, but I’m always open to new, decadent chocolate discoveries. Well, friends… we’d all better give Ireland a good, hard look. I discovered something rather life-altering when I visited last June, and just to be sure, I tasted as many kinds as I could when I was there last week. (Best. Work. Trip. Ever.) I’m talking about Irish Chocolate Biscuit Cake. These brownie-looking squares studded with graham-cracker-looking pieces are found in many (most?) bakeries in Ireland—I did my best to seek them out wherever possible… you know, for research. They are not, in fact, brownies, and they are not, in fact, laced with graham crackers. But to the un-indoctrinated, unsuspecting American eye, it’s what you’d first think. I saw them in the window last summer at Camerino in Dublin and was immediately bewitched—chocolate… with biscuits?! How could this not be spectacular? It was, indeed, a delightful little morsel, and I had an even better one at Butler’s Chocolate Café, where they cover theirs in a picture-perfect layer of tempered milk chocolate. Of course as any pastry nerd would, I immediately set about finding out whatever I could. It turns out that Chocolate Biscuit Cake is a common, well-loved Irish treat—where had I been all this time with all the not-knowing?? But don’t worry about me—I’m okay. I quelled my ignorance for good in Dublin and Cork last week, and I have a lot to tell you about Chocolate Biscuit Cake. And the best news is that it is SO easy to make, I’m talking stupid easy.

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Chocolate Biscuit Cake can be made in squares or slices, as is typical in bakeries, but it can also be made into a proper fancy cake. For instance, Prince William chose this, a beloved cake from his childhood, as the groom’s cake for his wedding. This did give the cake a bit of fame in the States temporarily, according to some articles that I found from 2011. (I couldn’t find any actual background or history on Chocolate Biscuit Cake though– if anyone knows its origin, please comment below.) That would be pretty awesome to make at some point, but for now, I hoped to re-create the bars that I’d had in the shops, especially the Butler’s version with the chocolate layer on top, albeit with ganache rather than tempered chocolate. Incidentally, I also discovered another dimension to this on my recent trip: variations. Holy shit, you can put marshmallows in these? Crushed malt balls? That’s right, there was what they called “Rocky Road Slice” (bar-shaped treats are often referred to as a “slice”), and I’m not sure what the malted ones were called, but they had Maltesers in them (Whoppers candy in America), and they made me want to cry a little. So this opens up a whole new world for future experimentation—I mean, what is stopping me from making S’mores Chocolate Biscuit Cake, for the love of god??

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Okay, I’m getting a little too worked up here. One more thing that I want to mention before diving into the recipe is that Ireland has a thriving chocolate industry, particularly for milk chocolate. This makes a lot of sense because of the magical Irish cows that graze on the magical Irish grass that grows ubiquitously due to the not-as-magical constant Irish rain. The Irish dairy industry produces some of the world’s best butter, milk, and cream, and therefore it follows that said milk would contribute to outstanding milk chocolate. If you visit Ireland (and you really should), make sure to check out some of the scrumptious chocolate shops.

So I mentioned above that the Chocolate Biscuit Cake looks like a brownie with graham crackers in it (which in and of itself should be a thing, but that’s a post for another day). I chose this particular recipe because it calls for three (three!) kinds of chocolate. The chocolate mixture consists of dark chocolate, milk chocolate, and white chocolate, butter (preferably Irish if we really want to live the dream), and Lyle’s Golden Syrup. I’ve seen recipes using treacle, and some with sweetened condensed milk; I didn’t think the latter sounded like a common Irish ingredient. (But someone please correct me if I’m wrong about that.) Treacle is a molasses-like syrup that I *thought* is hard to find in the States (but later found out is roughly equivalent to blackstrap molasses), so I settled on Lyle’s Golden Syrup because it’s fairly accessible, if not in your local well-stocked market, at least on Amazon. The beauty of Irish baking is that it’s simple, homey, and rustic—I wanted to come as close as possible to that.

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I would have loved to use actual Irish chocolate, but during my short business trip, I didn’t have an opportunity to search for good-quality baking chocolate, and I certainly couldn’t have brought home multiple pounds of it! That’s a mission for next time…. Anyway, I used instead Guittard 72% “Coucher du Soleil”, TCHO SeriousMilk Discs 39%, and Guittard 35% Soie Blanche, which always do me right.

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As for the biscuits, some recipes that I saw used only British digestive biscuits, but this one used a 50-50 combination of digestive and Rich Tea Biscuits, which I really like. You can use whatever mix you like or have on hand. Look for a brand called McVitie’s, though other British brands are fine as well; both of these can often be found in well-stocked supermarkets in the British section, or international stores like Cost Plus World Market.

The original recipe that I worked off of was overly rich and sweet, and it was so hard that I practically needed a saw to cut through it. I cut back on the golden syrup and butter a touch in order to lighten the sweetness and soften the texture, respectively. (The ones I had in Ireland were a bit more crumbly, but I like this fudgier texture even better.) Lastly, I sprinkled a little flaky salt on the finished bars, which brought the flavors out even more. My second batch was exactly what I had envisioned—rich, fudgy, crisp, decadent AF. I liked them best after chilling and thawing slightly.

And so, in honor of St. Patrick, I encourage you to make these chocolaty treats—I can’t think of a more delicious Irish dessert to celebrate the occasion. Hell, you can sprinkle shamrock quins on there if you want to make a festive green dessert!

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Irish Chocolate Biscuit Cake
Adapted from Roly’s Bistro (link no longer active, but it was from their recipe archive)
Yields 16-36 squares

It is essential to use the best-quality chocolate that you can here, as chocolate is the starring ingredient.

For the chocolate mixture:

  • 400 grams good-quality milk chocolate, chopped or wafers
  • 250 grams good-quality dark chocolate (around 72%), chopped or wafers
  • 200 grams good-quality white chocolate, chopped or wafers
  • 155 grams (11 tablespoons) unsalted butter, cut into cubes
  • 275 grams (¾ cup) Lyle’s Golden Syrup
  • 150 grams digestive biscuits
  • 150 grams rich tea biscuits

For the ganache topping:

  • 250 grams good-quality milk chocolate (even more for a firmer ganache), finely chopped
  • ½ cup heavy whipping cream
  • Flaky sea salt, such as Maldon

Line a 9×9″ square baking pan with parchment paper, leaving some paper hanging over the sides so you can later pull the whole slab up and out of the pan.

Place the milk, dark, and white chocolates in a large heatproof bowl set over a pot of gently simmering water on the stove (low-ish heat); make sure the bottom of the bowl does not touch the water and steam does not get into the bowl. Add the butter and golden syrup and stir everything together. Melt the ingredients, stirring occasionally until the mixture is smooth and homogenous.

In a separate bowl, break up the digestive and tea biscuits into pieces that are roughly the size of a quarter or euro coin. Mix them together evenly in the bowl and add them to the chocolate mixture; stir until all the biscuit pieces are coated in chocolate.

Pour the biscuit cake mixture into the prepared baking pan and spread it evenly and into the corners, flattening the top as much as possible. Make sure that the biscuits are evenly distributed throughout the pan, i.e. you don’t want patches of chocolate only and extra lumpy biscuit spots. Chill the biscuit cake in the fridge for about 2 hours or until firm.

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Meanwhile, make the ganache topping. Place the finely chopped milk chocolate in a medium bowl. Warm the heavy cream in a small saucepan just until it starts to boil, then pour it over the chocolate. Let it sit for 1-2 minutes to allow the chocolate to start melting, then whisk the chocolate and cream together, beginning in the center and working outward.

Pour the ganache over the biscuit cake, making sure to cover the entire surface evenly. Transfer the pan back to the fridge for 30 minutes to set the topping. Lightly sprinkle flaky sea salt over the top of the ganache after it has set (otherwise the flakes will sink into the chocolate).

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When ready to serve, remove the pan from the fridge and pull the biscuit cake up and out of the pan using the overhanging parchment paper. With a sharp knife, cut it into as many squares as you’d like– they are very rich, so a small morsel goes a long way! The biscuit cake can be served and stored (tightly covered) either cold or at room temperature.

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© Dafna Adler & Stellina Sweets, 2017.

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