Salt & Pepper Sandwich Cookies
Adapted from Baked Explorations

Ingredients:

For the Cake:
3 ½ cups all-purpose flour
¾ tsp salt
¼ tsp fleur de sel, plus more for decorating
2 tsp white pepper
½ cup dark unsweetened cocoa powder (I used Scharffenberger)
1 ½ cups (3 sticks) unsalted butter, cut into 1-inch cubes, cool, but not cold
1 cup granulated sugar
1 ¾ cups confectioners’ sugar
3 large egg yolks
1 tbsp pure vanilla extract
3 oz good-quality dark chocolate (60-72% – I used 70% Scharffenberger), melted

For the Filling:
5 oz vegetable shortening, at room temperature
4 tbsp (1/2 stick) unsalted butter, cut
3 ¼ cups confectioners’ sugar, sifted
½ tsp salt
1 tbsp pure vanilla extract
1 tsp light rum

Preparation:

To Make Cookies:

In a large bowl, mix the flour, salt, fleur de sel, white pepper, and cocoa powder, using a whisk, and then aerate the dry ingredients. Set aside.

In the bowl of a standing mixer, fitted with a paddle attachment, beat the butter and both sugars together until light and fluffy – about 3 minutes or so. Scrap down the blow, add egg yolks, one at a time, beating until each is incorporated into the mix. Add the vanilla extract, then melted chocolate, and beat until uniform in color. Using a spatula, scrape down the sides (and bottom!) of the bowl, add the remaining dry ingredients and mix until just incorporated. [When adding dry ingredients, I recommend starting the mixer on the lowest speed possible, to create the least amount of mess.]

Loosely shape the dough into two balls, wrap them tightly in plastic, and refrigerate for at least 3 hours, but I gave mine an overnight rest.

Preheat the oven to 350 degrees F. Line 2 baking sheets with parchment paper. Unwrap on ball of dough, but maintain the plastic on it. Give the ball about a 40 minute rest on your counter. Mine was rock hard. It’ll feel rock hard after those 40 minutes too, but you can beat it (um, yes, beat it) with a rolling pin to smush it down. Sprinkle some flour all over the disk – not a tiny dusting, but not a voluminous amount either. Get a few large pieces of wax paper and put them on top and bottom of the now-flattened disk. With the top of the plastic wrap still on the dough, roll the dough out, using the rolling pin (now the dough is between sheets of wax paper) to about ¼ inch thickness. [The book notes that the dough will be slightly sticky. Mine was insanely sticky, downright impossible to work with. The wax paper solution fixes all of that AND prevents a royal mess in your kitchen.] Anyway, using a 2-inch round cookie cutter, prepare your sandwich tops and bottoms, and transfer them to the prepared baking sheets, leaving at least a 1 ½ inch space (2 inches will be better). HELPFUL TIP: Use a small frosting spatula to lift and transfer the unbaked cookies to the baking sheet. Continue the cookie cutting process with the remaining dough – and extra dough scraps can be re-chilled and rerolled again.

Sprinkle the tops of cookies with a little fleur de sel, then bake them for 10-12 minutes, rotating the sheets halfway through the baking time. The tops of the cookies should look a bit dry, and possibly cracked. Place the baking sheets on wire racks to cool for 5 minutes, and then, using a spatula, transfer the cookies to the racks to col completed before filling them.

To Make Filling:

In the bowl of a standing mixer fitted with the paddle attachment, beat the shortening with the butter until it is smooth and lump free. Add the sugar, in 3 parts, mixing each part until just incorporated. Add the salt, vanilla, and rum and beat again for 10 seconds. The filling should be thick but spreadable (like Oreo filling). If it’s too thick, add a drop or two of water, if you like. If, however, your mixture is too thin, feel free to add a few spoons of confectioners’ sugar to achieve the right consistency.

Using a small spoon, like the tiny cookie scoop, apply about 2 tablespoons of filling to the flat side of the cookie. Place another cookie, flat side down, on top of the filling and press down slightly to allow the filling to spread all over the center to the outer edges. Repeat until all the cookies are made.