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

In a medium bowl, whisk together the flour, instant coffee granules, cocoa powder, and baking powder until combined.

In a large mixing bowl, cream together the unsalted butter and granulated sugar until light and fluffy, about 2-3 minutes. Then, add the eggs one by one and the vanilla extract, mixing well.

Gradually add the dry mixture into the wet mixture, stirring gently until just combined, avoiding overmixing.

Drop spoonfuls of dough onto the prepared baking sheets, spaced about 2 inches apart.

Bake for 10-12 minutes or until edges are golden and centers are soft. Let cool for 5 minutes before transferring.

In a small saucepan, combine brewed espresso with sugar and stir until dissolved. Let it cool to room temperature.

Spread a layer of mascarpone cheese on the flat side of one cookie, drizzle with cooled espresso syrup, then top with another cookie.

Dust assembled cookies with cocoa powder before serving.