Preheat oven to 350°F and line muffin tin with paper liners.
Mix flour, sugar, cocoa, baking soda, and salt in a bowl.
Combine cooled coffee, oil, vinegar, and vanilla in another bowl.
Stir wet into dry until just combined; do not overmix.
Divide batter into muffin cups, filling ⅔ full.
Bake 18–22 minutes until toothpick comes out clean.
Cool 5 minutes in pan, then transfer to wire rack.
Hollow center of cupcakes with a knife.
Beat mascarpone until smooth, add cream, sugar, Kahlua, vanilla.
Beat until thick and pipeable; chill if too thin.
Pipe frosting on cupcakes using piping bag.
Dust with cocoa and decorate with chocolate or espresso beans.