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 until well combined.

In a large mixing bowl, cream together the unsalted butter and granulated sugar until light and fluffy, about 3-4 minutes. Add the eggs one at a time, mixing well after each addition, followed by the vanilla extract.

Gradually fold the dry ingredient mixture into the wet mixture using a spatula until just combined.

Scoop even amounts of the dough onto the prepared baking sheets, spacing them about two inches apart.

Bake for 10-12 minutes until the edges are golden brown and the centers remain soft.

Allow the cookies to cool on the baking sheets for about 5 minutes before transferring to a wire rack to cool completely.

Prepare the espresso syrup by heating brewed coffee and sugar in a small saucepan over low heat until dissolved, then let it cool.

Once cooled, spread mascarpone cheese on one cookie, drizzle with espresso syrup, and top with another cookie.

Dust the assembled cookies with cocoa powder before serving.