My (Bitter)Sweet & Salty Muse: Walnut Shortbread Sandwich Cookies with Caramel Cream

Apparently I’ve been living under a large rock for quite some time, because even throughout my many pastry “research” excursions in San Francisco, I had only recently become familiar with Yigit Pura and his magnificent pastry shop, Tout Sweet. I first sampled his fabulous French macarons and other creations at the SF Ferry Building Farmers’ Market, one of which is the “WTF” Cookie, aka What the Flavor. Among his dazzling treats, this one looks somewhat monochromatic and understated, but don’t let that fool you– it is one of the loveliest cookies I have ever tasted. Seriously, ever. Two salt-sprinkled walnut shortbread cookies sandwich a burnt caramel filling to induce a complex mélange of nutty, salty, sweet, buttery; these mere words are woefully insufficient, really. I was content to have one once in a while when I was able to roll by Chef Pura’s Palo Alto shop after work (or at least I convinced myself that this would be enough– you know, to avoid spiraling into a deep depression brought on by WTF deprivation)… but then Tout Sweet had to go and post an Instagram photo a few weeks ago of this cookie that I’d had to squirrel away in the back of my mind, and I could no longer contain my cravings– I had to try making my own.

I found Yigit Pura’s recipe for walnut shortbread online (it is not in his book, Sweet Alchemy), which is a citrus version, so I simply omitted the citrus zest. His filling seems to be a caramel cream of sorts, rather than a pure caramel, which would set better in a sandwich cookie. Pierre Hermé makes an amazing salted butter caramel cream to fill macarons, which I adapted slightly. Since these cookies already have a strong hit of salt, I used all unsalted butter rather than a combination of salted and unsalted.

I have been struggling with caramel for the past year or two for some reason, so I was a bit apprehensive to make this filling, especially being that it’s a Pierre Hermé recipe. There is nothing to fear, however– it’s not you, it’s me. While I work on my caramel issues, don’t be afraid. I wanted to mimic the slightly bitter/burnt flavor of Yigit Pura’s cookie filling, so I let the caramel cook for longer than normal. (It also didn’t help that my candy thermometer was throwing a temper tantrum…) When I tasted the finished caramel cream, it was too bitter to eat on its own, and I feared that I had, in fact, burnt it. However, when sandwiched between the nutty, toasty, salty shortbread, it was perfection. I couldn’t believe it! You can, of course, adjust the level of bittersweetness to your liking.

I was not a huge fan of walnuts in the past—I’ve never snacked on them, or god forbid!! put them in brownies. However, a few recipes in particular (see here, here, and here) have persuaded me to embrace walnuts’ nutty, versatile, and crunchy virtues. The key is toasting them nice and dark—it brings out a certain smokiness in the nuts that their raw counterparts lack, and it makes all the difference in flavor. In this shortbread recipe, you’ll chop the toasted walnuts finely and incorporate them right into the dough, which lends a wonderfully deep and complex flavor to the baked cookies. The dough comes together very easily and freezes well, so you can have some on-hand any time you crave a WTF… or five. 😀

Walnut Shortbread Sandwich Cookies with Caramel Cream
Yields 24-30 sandwich cookies

I had a ton of caramel cream left over, so I cut the original Pierre Hermé recipe in half here, which is easy because it’s written in weights. If you wish to make the full batch, double the shortbread dough for LOTS of cookies. There won’t be any complainers. 🙂

For the filling (adapted from Macarons by Pierre Hermé):

• 150g (about ¾ cup) granulated sugar
• 175g (about ¾ cup) heavy whipping cream
• 32g (2 tablespoons) unsalted butter, at room temperature (original recipe calls for salted here)
• 145g (10 tablespoons/1 ¼ sticks) unsalted European-style butter, softened (***check this)

For the shortbread cookies (adapted from Yigit Pura in Sunset Magazine):

• 1 cup (2 sticks/16 tablespoons) unsalted butter, at room temperature
• ⅔ cup granulated sugar
• 2 large egg yolks
• 2 cups all-purpose flour, sifted
• ⅔ cup walnut pieces, toasted medium-dark (or to taste) and finely chopped
• 1 teaspoon flake salt, such as Maldon

Make the caramel cream filling: Bring the heavy cream to a boil in a small saucepan and set aside.

Melt about ½ cup of the sugar in a medium saucepan or a large sauté pan over medium heat. When it’s about half melted, add the rest of the sugar to the pan gradually, moving it around gently. Let it melt completely, stirring occasionally and breaking up clumps of sugar; take care not to splash sugar onto the sides of the pan. Cook the sugar until it has reached a deep amber color— this is where the flavor development happens. I let mine get really dark to achieve that bittersweet “burnt” flavor. Remove the pan from the heat and add 32g of butter to the pan—it will bubble up and spit as you stir it in. Once the butter is blended, whisk in the cream, stirring continuously; it will also get a little uppity here. It’s okay if the caramel seizes up and hardens a bit, as you’ll put it back on the stove in the next step.

Place the pan back on a low burner and cook until it reaches 226°F on a candy thermometer. It’s okay to gently swirl the pan occasionally to make sure the caramel is cooking evenly, but do not stir continuously. This step is where mine got a little crazy. My thermometer kept fluctuating wildly, dropping 10° suddenly at times. I pulled the pot off the heat immediately as soon as it hit 226°F, and it was quite dark and bittersweet.

Carefully pour the hot caramel into a shallow dish and let it cool slightly. Place a piece of plastic wrap directly on the caramel surface. Let the caramel firm up and chill completely in the fridge, several hours or overnight.

When the caramel is ready to use, place the rest of the butter in the bowl of a stand mixer fitted with the paddle attachment. Beat for 8-10 minutes on medium-high speed; it will lighten considerably in color. Incorporate the caramel in 2 additions, beating each time until the caramel is blended. The caramel cream should be smooth, spreadable, and somewhat fluffy. Transfer to a bowl and cover with plastic wrap until ready to use.

Make the shortbread: Place the butter and sugar in the bowl of a stand mixer fitted with the paddle attachment. Beat on medium speed until light and fluffy, about 2-3 minutes. Scrape down the sides and bottom of the mixing bowl. Add the egg yolks and mix until just until incorporated. Scrape again and beat for another few seconds to make sure everything is evenly combined. Add the flour and walnuts and mix on low speed just until the dry ingredients are blended and the dough starts to come together. Do not over-mix—the dough should not form a ball.

Dump the shaggy dough onto your work surface and gently bring together into two balls with your hands. Flatten each ball into a disk about 6” in diameter and wrap tightly with plastic wrap. Chill the dough disks until firm, a few hours or overnight.

Preheat an oven to 300°F and position a baking rack in the center. Line 2 rimless cookie sheets with parchment paper. You can bake both sheets at the same time (position upper and lower racks accordingly), but I prefer one sheet at a time.

Remove one dough disk from the fridge and allow it to soften slightly at room temperature, about 10 minutes. Roll out the dough on a lightly floured work surface to a thickness of about ¼-inch. Using 1½- or 2-inch round or square biscuit/cookie cutters (or really any shape you want, for that matter), cut out your shapes and transfer them to one of the prepared cookie sheets, spaced about 2” apart. I used a combination of plain and fluted round cutters. Gather and reroll the scraps, chilling the dough if needed. (It does get soft and sticky, and you’ll get the nicest cutouts with firm dough, as well as with sharp cutters.) Once filled, put the cookie sheets in the freezer for about 10 minutes to firm up the dough.

Sprinkle all or half of the cookies with salt flakes, depending on whether you want both tops and bottoms salted (but don’t skimp– they are best with a salty, crunchy hit!) and bake 18-22 minutes depending on your desired degree of crispness; rotate the pan halfway through, and swap the pans if baking 2 sheets at the same time. The cookies will not get very dark.

Let the shortbread cutouts cool on the pan set over a wire cooling rack for 5-10 minutes, then transfer the whole sheet of parchment directly to the rack to cool completely. Repeat the process with the remaining dough.

To assemble the cookies, transfer the caramel cream to a pastry bag fitted with a medium plain or star tip of your choice. I used a coupler so I could switch tips midway through for a little variety. Match up cookie pairs of similar size and thickness.

Flip one cookie from each pair bottom-side-up and pipe a mound or spiral of caramel cream in the center (about 1 teaspoon for 1½ cookies). Alternatively, you can spread the filling onto the cookies with a small offset spatula or a spoon. Place the second cookie on top and gently press them together so that the filling squeezes out to the cookie edges.

Let the caramel cream set for a few hours before serving; it will remain fairly soft, however. The sandwich cookies will keep for about 3 days stored in an airtight container.

Make ahead: You can prepare the caramel (or even the completed caramel cream filling) and shortbread dough up to a few days ahead (store in the fridge), then finish the filling and roll out/bake/assemble the cookies on the day you plan to serve them.

© Dafna Adler & Stellina Sweets, 2015.