Preheat the oven to 350°F and prepare 2 large baking sheets with parchment paper. Set aside.
In a medium mixing bowl, whisk together the flour, espresso powder, baking soda, baking powder, and salt. Set aside.
1-2/3 cup all-purpose flour, 1 tbsp. instant espresso powder, 1/2 tsp. baking soda, 1/4 tsp. baking powder, 1/2 tsp. table salt
In a large mixing bowl, beat the softened butter, light brown sugar, and granulated sugar with a hand mixer until light and fluffy.
1/2 cup unsalted butter, 1/2 cup packed light brown sugar, 1/4 cup granulated sugar
Add the egg, vanilla extract, and almond extract to the butter mixture, mixing until combined.
1 large egg, 1/2 tsp. vanilla extract, 1/2 tsp. almond extract
Gradually add the dry ingredients to the wet ingredients, mixing with a large spoon until a dough forms.
Use a 1.5-ounce cookie scoop (same as 3 tbsps.) to portion out equal-sized balls of dough. Place 6 cookies on each prepared baking sheet.
Bake for 13-14 minutes, then transfer the cookies to a cooling rack to cool completely.
For the frosting - in a large mixing bowl, combine the mascarpone, heavy whipping cream, rum extract, and confectioners' sugar. Beat with a hand mixer until fully combined and stiff peaks form.
1 cup mascarpone cheese, 2/3 cup heavy whipping cream, 1/2 tsp. rum extract, 1 cup confectioners' sugar
Transfer the frosting to a piping bag fitted with a round tip. Once the cookies have cooled, pipe a spiral of frosting onto each one.
Lightly dust the tops of the cookies with cocoa powder to finish.
1/4 cup unsweetened cocoa powder