Preheat your oven to 350°F (175°C) and line your baking sheets with parchment paper.

In a medium bowl, whisk together the all-purpose flour, instant coffee granules, cocoa powder, and baking powder.

In a large mixing bowl, beat together the unsalted butter and granulated sugar until light and fluffy. Add eggs one at a time and stir in vanilla extract.

Gradually add the dry mixture into the creamed mixture, mixing on low speed until just combined.

Drop rounded portions of dough onto the prepared baking sheets, leaving enough space between each dollop.

Bake for 10-12 minutes until the edges are golden and centers are slightly soft. Cool on sheets for 5 minutes before transferring to a wire rack.

In a small saucepan, combine brewed espresso with sugar over medium heat until dissolved, then cool slightly.

Spread a generous amount of mascarpone cheese on one cookie, drizzle some espresso syrup, and top with another cookie. Dust with cocoa powder before serving.