Melt the butter in the microwave or in a small saucepan over low-medium heat. Pour the melted butter into a mixing bowl and let it cool down to room temperature in the fridge (about 20 minutes).

Once the butter has reached room temperature, add the granulated sugar and dark brown sugar and whisk together for 1 minute using a spatula or a stand mixer with the paddle attachment.

Add the egg and vanilla extract, mixing until combined.

In a separate bowl, stir together flour, baking powder, baking soda, instant espresso powder, and salt. Add the dry ingredients to the wet mixture and mix until just combined.

Using a 2 tbsp/1.3 ounce cookie scoop, scoop out 11 cookies and place them on a tray lined with baking paper. Roll them into balls and place in the fridge to set for 1 hour.

Preheat the oven at 180ºC/355ºF and prepare a baking sheet with baking paper. Place 6 cookies per baking tray and bake one tray at a time for 10-11 minutes.

Once baked, let them cool on the baking tray for 3 minutes before lifting them onto a cooling rack to cool completely.

In a medium bowl with an electric mixer or a stand mixer using the whisk attachment, whip together all of the ingredients until it reaches stiff peaks.

When ready to serve, add the cream to a piping bag fitted with a piping tip. Pipe the mascarpone cream on top of the cookies in a swirl, then dust with cocoa powder.