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

In a mixing bowl, combine softened unsalted butter and granulated sugar. Beat until light and fluffy, about 2-3 minutes.

Dissolve the espresso powder in hot water. Add this mixture along with the eggs and vanilla extract to the creamed butter and sugar. Blend until well combined.

In a separate bowl, whisk together all-purpose flour, baking powder, and salt. Gradually add this to the wet mixture, mixing gently until combined.

Gently fold in the mascarpone cheese.

Scoop generous portions of dough onto the prepared baking sheet, leaving 2 inches between each cookie.

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

Let the cookies cool on the baking sheet for 5 minutes before dusting with cocoa powder and transferring to a wire rack.