Preheat your oven to 180ºC (355ºF) and line a baking sheet with parchment paper.

Melt the butter and allow it to cool to room temperature. Blend with granulated and dark brown sugars until smooth.

Add the egg and vanilla extract, then beat until smooth.

In a separate bowl, whisk together the dry ingredients and fold them into the wet mixture.

Scoop the dough into balls and place on the baking sheet. Chill the dough for 30 minutes.

Bake the cookies for 10-11 minutes, until golden around the edges.

Combine mascarpone, vanilla, confectioners' sugar, agave or honey, and heavy cream; whip until stiff peaks form.

Pipe the mascarpone cream onto cooled cookies and dust with cocoa powder.