Preheat the oven to 350 degrees. Line a 12-cup muffin tin with cupcake papers.

1. In the bowl of a stand mixer fitted with the whisk attachment, cream the butter and sugar until light and fluffy.
2. Add eggs one at a time, beating well after each addition.
3. Beat in the vanilla, followed by the melted chocolate.
4. In a separate bowl whisk together the cake flour, baking powder and salt.
5. Add the dry ingredients and the milk to batter in several alternating addition, mixing well after each.
6. Spoon batter into the prepared pan, filling each cup about half full.
7. Bake until the tops of the cupcakes spring back when pressed lightly, about 18 to 20 minutes. Cool completely.
8. Meanwhile make soaking syrup: Bring water and sugar to a boil in a small saucepan and simmer until the sugar dissolves, 2–3 minutes.
9. Remove from heat and stir in the espresso powder and liqueur, if desired. Set aside to cool.

To assemble:

1. Gently pull the cupcake paper halfway down on each cupcake and cut the cake in half.
2. Using a pastry brush, lightly soak the top and bottom of each cupcake with flavored syrup.
3. Place a scoop of espresso ice cream on the bottom half of each cupcake, then place the top over it and press gently.
4. Ease the cupcake paper back into place and return the cupcakes to the pan.
5. Pipe whipped cream onto each cupcake, top with sprinkles and freeze until firm, 2–3 hours.