Preheat your oven to 350°F (177°C) and prepare two 6-inch cake pans by greasing with butter and lining with parchment paper.

Sift together 1.5 cups of cake flour, 1.5 teaspoons of baking powder, and a pinch of salt in a medium bowl and set aside.

Mix 2 tablespoons of instant espresso powder with 0.25 cups of boiling water until dissolved and cool.

Beat 0.5 cups of softened unsalted butter with 1 cup of sugar until creamy, about 3-5 minutes.

Add 1 teaspoon of vanilla extract and then add 3 eggs one at a time, mixing well after each.

Alternately add the flour mixture and 0.5 cups of milk to the butter mixture until smooth, then fold in cooled espresso.

Divide batter evenly between pans and smooth the tops. Bake for approximately 20 minutes or until a toothpick comes out with a few moist crumbs.

Let cakes cool in the pans for 5 minutes, then invert onto wire racks to cool completely.

Whip 1 cup of mascarpone cheese, gradually adding 1 cup of powdered sugar and 2 tablespoons of chilled coffee until smooth, then fold in 1 cup of heavy whipping cream.

Slice each cooled layer in half and moisten with liquor or coffee, layer frosting between and on the exterior of the cake. Dust with cocoa powder before serving.