Stareos

To make the chocolate shortbread: In a bowl, stir together the flour, salt and cocoa powder and set aside. Combine the butter and sugar in the bowl of a stand mixer fitted with the paddle attachment and beat on low speed until the butter and sugar begin to incorporate, about 15 seconds. Add the dry ingredients and continue to mix until the dough comes together, about 3 minutes. It will look dry just before it comes together.

Line 2 baking sheets with parchment paper. On a lightly floured work surface, roll out the dough 1⁄4 inch thick. Using a 2-inch star cutter, cut out as many cookies as possible. Gather together the scraps, reroll, and continue cutting out cookies until you have 36 cookies. Place the cookies on the prepared baking sheets, spacing them 1 inch apart. Refrigerate until firm, at least 1 hour.

Preheat the oven to 300 F. Bake the shortbread until firm, about 35 minutes. At the midway point, switch the baking sheets between the racks and rotate them 180 degrees to ensure even baking. Let cool on the baking sheets to room temperature.

To make the filling: In a small bowl, stir together the mascarpone, sugar and vanilla until smooth.

Turn 18 of the cookies bottom-side up on a work surface. Using a table knife or a small icing spatula, spread about 1 tablespoon of the filling on the bottom of each cookie. Top with the remaining cookies, bottom-side down.