- For Cookies:
- 2 1/3 cups all-purpose flour
- 1/4 teaspoon kosher salt
- 16 tablespoons (2 sticks) unsalted butter, at room temperature
- 1/2 cup sugar
- 6 ounces dark chocolate
- For Mocha Filling:
- 4 tablespoons (1/2 stick) unsalted butter, at room temperature
- 1 tablespoon cocoa powder
- 2 tablespoons milk
- 2 teaspoons instant espresso
- 1- to 1 1/2-cups confectioners’ sugar
Adjust oven racks to upper and lower middle positions and preheat oven to 350°F. Line two baking sheets with parchment paper.
Melt chocolate in microwave or in a double boiler, whisking occasionally until smooth then let cool slightly. In a large bowl, beat together butter and sugar with a wooden spoon until light and fluffy, about 3 minutes. Beat in cooled chocolate until evenly distributed.
In a small bowl mix together salt and flour. Beat flour into chocolate mixture in two additions, continuing until dough just comes together. Divide dough into two balls and chill for 30 minutes.
Flour a large work surface. Using a rolling pin, roll out dough into a 1/8-inch thick rectangle. Use a 2 inch fluted cookie cutter (or other cutter shape of your choice) to cut out approximately 24 cookies. Arrange on baking sheets leaving 1-inch between each cookie. Bake cookies until dry looking on the surface but not cracked, about 15 minutes. Let cookies cool completely.
Make Mocha Filling: In a medium bowl, beat together butter, cocoa powder, milk, and instant espresso. Beat in one cup confections sugar. Taste and, if desired, beat in another half cup of confectioners sugar.
Assemble Cookies: Top half of the cookies with mocha filling. Use the other halves to complete the sandwiches.