Preheat oven to 350°F (175°C). Line a muffin tin with cupcake liners.
In a bowl, whisk together flour, baking powder, baking soda, and salt.
In another bowl, beat butter and sugar until light and fluffy. Add eggs one at a time, beating well after each addition. Mix in vanilla extract.
Alternate adding the flour mixture and milk to the butter mixture, beginning and ending with the flour mixture. Mix until just combined.
Divide batter evenly among cupcake liners. Bake for 18-20 minutes or until a toothpick inserted into the center comes out clean. Let cool completely.
Brush cooled cupcakes with brewed coffee.
For the frosting, beat mascarpone cheese until smooth. In another bowl, whip heavy cream, powdered sugar, and vanilla extract until stiff peaks form. Fold whipped cream into mascarpone until well combined.
Pipe frosting onto cooled cupcakes and dust with cocoa powder.