Step 1: Bake the Cake

1. Preheat oven to 350°F (175°C). Grease and line two 8-inch round cake pans with parchment paper.
2. In a bowl, whisk together flour, baking powder, and salt.
3. In another bowl, cream together butter and sugar until light and fluffy.
4. Add eggs one at a time, mixing well after each. Stir in vanilla extract.
5. Gradually mix in dry ingredients, alternating with milk until just combined.
6. Divide batter evenly between the prepared pans and bake for 20-25 minutes, or until a toothpick inserted in the center comes out clean.
7. Let cakes cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.

Step 2: Make the Coffee Syrup

1. In a small bowl, mix brewed espresso, coffee liqueur (if using), and sugar. Stir until sugar dissolves.
2. Set aside to cool.

Step 3: Prepare the Mascarpone Cream

1. In a bowl, whisk mascarpone cheese, powdered sugar, and vanilla extract until smooth.
2. In a separate bowl, whip heavy cream until stiff peaks form.
3. Gently fold the whipped cream into the mascarpone mixture until smooth and fluffy.

Step 4: Assemble the Cake

1. Place one cake layer on a serving plate. Brush generously with coffee syrup.
2. Spread half of the mascarpone cream over the cake.
3. Place the second cake layer on top and brush again with coffee syrup.
4. Spread the remaining mascarpone cream evenly over the top and sides.

Step 5: Decorate & Serve

1. Dust the top with cocoa powder using a fine sieve.
2. Garnish with chocolate shavings for extra indulgence.
3. Refrigerate for at least 2 hours before slicing for the best flavor and texture.