• Preheat oven to 340ºF (170ºC).
• Line two baking sheets with parchment paper and have a pastry bag with a plain tip (about 1/2-inch, 1 cm) ready.

Prepare the macaron shells.

• Grind together the powdered sugar with the almond powder and cappuccino powder so there are no lumps; use a blender or food processor. 
• Using a mixer beat the egg whites until they begin to rise and hold their shape. While whipping, beat in the granulated sugar until very stiff and firm, about 2 minutes.
• Fold the dry ingredients, in two batches, into the beaten egg whites with a rubber spatula. When the mixture is smooth and there are no streaks of egg white, stop folding and scrape the batter into the pastry bag. (standing the bag in a tall glass helps if you’re alone).
• Pipe the batter on the parchment-lined baking sheets in 1-inch (3 cm) circles (about 1 tablespoon each of batter), evenly spaced one-inch (3 cm) apart.
• Rap the baking sheet a few times firmly on the counter top to flatten the macarons and sprinkle espresso in top of each. Let them rest at room temperature. A skin needs to form, and it can take 30-90 minutes, depending on the weather. If you touch them lightly and the top has dried, and nothing sticks to your finger, they’re ready to bake. Bake them for 15-18 minutes. Let cool completely then remove from baking sheet.

Prepare the chocolate filling.

• Heat the cream in a small saucepan. When the cream just begins to boil at the edges, remove from heat and add the chopped chocolate. Let sit one minute, then stir until smooth. Stir in the pieces of butter. Let cool completely before using.
• Spread a bit of batter on the inside of the macarons then sandwich them together.
• Let them stand at least one day before serving, to meld the flavors.