For the Cookies-
¼ cup + 3 tablespoons black cocoa powder, plus more for dusting
2 tablespoons unsalted butter, melted
5 tablespoons unsalted butter, softened
½ cup firmly packed light brown sugar
¼ teaspoon kosher salt
1 large egg
1 teaspoon vanilla extract
1½ cups all-purpose flour
¼ teaspoon ground cardamom (optional)
¼ teaspoon ground pink peppercorns (optional)
In a small bowl, whisk together the black cocoa and melted butter; cool slightly. In a medium bowl, whisk together flour, ground cardamom, and ground pink peppercorns.
In the bowl of a standing mixer fitted with the paddle attachment, beat softened butter, brown sugar, and salt at medium speed until fluffy, 3 to 4 minutes, stopping to scrape down sides of bowl. Beat in cocoa mixture. Add egg and vanilla, beating until well combined. Add flour and spices, beating until fully incorporated, forming a smooth dough.
Scrape dough onto a sheet of parchment paper. Place another sheet of parchment paper on top of dough. Roll dough (between the parchment sheets) to ⅛” thickness and transfer dough (between the parchment sheets) to a baking pan. Freeze the dough for about 30 minutes, until set.
Preheat the oven to 325 degrees F. Retrieve the dough from the freezer, carefully flip the two sheets of parchment over (with the dough in the middle) and peel off the top sheet of parchment. Dip your cookie cutter (a 3” cutter works well) in black cocoa to prevent it from sticking. Cut dough and place cookies about ½“ apart on a parchment lined baking sheet. (Scraps can be rerolled, frozen again, then cut and baked.)
Bake cookies for about 10-12 minutes, just until a slight indentation is left when you gently press the cookie with your finger. Set baking sheet on a cooling rack allowing cookies to cool completely. Prepare Vanilla Filling. Fill a piping bag with a round tip and pipe filling on the flat side of half of the cookies. Place remaining cookies, flat side down, on top of filling.
For the Vanilla Filling-
1 cup unsalted butter, softened
4 cups confectioners’ sugar
1 teaspoon vanilla bean paste
⅛ teaspoon kosher salt
In the bowl of a stand mixer fitted with the paddle attachment, beat butter at medium speed until creamy, 5 to 6 minutes. Gradually add confectioners’ sugar, beating until combined. Add vanilla bean paste and salt, beating until smooth.