In a large bowl, cream together butter and both sugars until light and fluffy. Add the egg and vanilla and beat well.

In a separate bowl, whisk together the flour, baking powder, baking soda, espresso powder and salt. Add to the creamed butter mixture and stir until well combined. Scoop out into 1 tablespoon balls and place on a baking sheet close together. Chill for 1 hour before baking.

Preheat oven to 350°F. Line 2 baking sheets with parchment paper and place six cookie balls on each. Bake until lightly golden brown around the edges, about 10-12 minutes, making sure to rotate pans halfway through baking. Allow to cool for 5 minutes on the sheets before transferring to a wire rack to cool completely.

To make the frosting, beat the mascarpone, heavy cream, powdered sugar, vanilla and honey until thick and soft peaks form. Transfer to a piping bag and pipe out a thin layer onto each cooled cookie. Dust the tops with cocoa powder and serve. Leftovers can be refrigerated for up to 4 days. Enjoy!