For the sponge cake:

1 cup all-purpose flour

1 1/2 tsp baking powder

1/4 tsp salt

4 large eggs, room temperature

3/4 cup granulated sugar

1 tsp vanilla extract

1/4 cup whole milk, warmed

1/4 cup butter, melted and cooled

For the espresso soak:

3/4 cup brewed espresso or strong coffee, cooled

2 tbsp coffee liqueur (optional)

1 tbsp sugar (optional)

For the mascarpone cream:

1 cup mascarpone cheese, cold

1 cup heavy cream, cold

1/3 cup powdered sugar

1 tsp vanilla extract

To finish:

Unsweetened cocoa powder (for dusting)

Optional: chocolate curls or shavings