Step 1: Preheat and Prepare

1. Preheat your oven to 350°F (175°C).
2. Line a 12-cup muffin tin with cupcake liners.

Step 2: Mix the Dry Ingredients

1. In a bowl, whisk together flour, baking powder, and salt.
2. Set aside.

Step 3: Prepare the Batter

1. In a large mixing bowl, beat butter and sugar until light and fluffy.
2. Add eggs, one at a time, beating well after each addition.
3. Mix in the vanilla extract.
4. Gradually add the dry ingredients, alternating with milk, starting and ending with the dry ingredients. Mix until just combined.

Step 4: Bake the Cupcakes

1. Divide the batter evenly among the prepared cupcake liners.
2. Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
3. Let the cupcakes cool completely before soaking and frosting.

Step 5: Soak the Cupcakes

1. Using a fork or skewer, poke small holes on the top of each cupcake.
2. Brush the tops with the cooled espresso (mixed with coffee liqueur, if using), allowing it to soak in.

Step 6: Make the Mascarpone Frosting

1. In a mixing bowl, beat mascarpone cheese, heavy cream, powdered sugar, and vanilla extract until smooth and fluffy.
2. If using, add coffee liqueur for extra flavor.
3. Transfer the frosting to a piping bag fitted with a round tip.

Step 7: Frost and Decorate

1. Pipe the mascarpone frosting onto each cupcake.
2. Dust with unsweetened cocoa powder.
3. Garnish with chocolate shavings or crushed ladyfingers for an extra decorative touch.

Step 8: Chill and Serve

1. For the best flavor, chill the cupcakes in the refrigerator for at least 1 hour before serving.
2. Enjoy with a cup of espresso!