For cookie shellsIn a large bowl cream together the butter and sugar using an electric mixer (or use a stand mixer) until well combined.1 cup (226 g) unsalted butter, softened, 1 cup (200 g) granulated sugar

Add the egg and vanilla to the butter mixture and stir well.1 large egg, ¾ teaspoon vanilla extract

In a separate medium-sized bowl, whisk together the flour, black cocoa powder, baking powder, baking soda, and salt.1 ¾ cups (220 g) all-purpose flour, ⅔ cups (67 g) black cocoa powder, ½ teaspoon baking powder, ¼ teaspoon baking soda, ¾ teaspoon salt

Gradually add the dry ingredients to the wet ingredients, mixing until well combined.

Divide the dough into two equal parts, form each into a disk about 1″ thick, and wrap in plastic wrap. Chill for at least 1 hour before proceeding.

Preheat the oven to 350°F (175°C) and line cookie sheets with parchment paper. Set aside.

Working with one disc of dough at at time, unwrap dough and transfer to a clean, lightly floured surface. Lightly sprinkle flour over the dough and use a rolling pin to roll the dough to about ⅛-1/16″ (0.2cm) thickness. To help keep the dough from sticking to the counter, periodically use a spatula to scrape beneath the dough and loosen it from the counter.

To make the pattern shown on my cookies: take a clean, grid-patterned cooling rack and flip it upside down. Gently press into the cookie dough, then gently lift, rotate the cooling rack, and press again before gently lifting and removing. Alternatively, use an embossed rolling pin or skip the design altogether.

Usea small round cookie cutter (I use 1 ¾” (4.5cm) circles) to cut out circles and transfer to baking sheet, spacing 1” (2.5cm) apart. Once you’ve made as many cuts as possible, be sure to recombine the dough scraps, roll out again, and cut out more cookies to maximize the dough yield.

Bake the cookies in the preheated oven for 8-10 minutes. Allow them to cool completely before filling.

For the Filling:In a medium-sized bowl, cream together the softened unsalted butter and shortening using an electric mixer.½ cup (113 g) unsalted butter, ¼ cup (45 g) vegetable shortening

Gradually add the powdered sugar, stirring until well-combined.2 cups (250 g) powdered sugar

Stir in vanilla extract and salt.½ teaspoon clear vanilla extract, ⅛ teaspoon salt

To Assemble:Pipe or spread a thin layer of the filling on the flat side of a cooled cookie, and then sandwich with another cookie, flat side down.

Repeat with the remaining cookies and filling. Enjoy!