Preheat oven to 225 degrees.
Process the powdered sugar, almond powder and cocoa in a blender or food processor so there are no lumps. Set aside.
In the bowl of a standing electric 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.
Carefully fold the cocoa mixture, in two batches, into the beaten egg whites with a flexible rubber spatula.
When the mixture is just smooth and there are no streaks of egg white, stop folding and scrape the batter into a pastry bag (standing the bag in a tall glass helps).
Pipe the batter onto parchment-lined baking sheets into 1-inch circles (about 1 tablespoon each of batter), evenly spaced 1 inch apart.
Once piped, let the rounds sit for 30 minutes to develop a crust.
Rap the baking sheet a few times firmly on the countertop to flatten the macarons, then bake them for 15 to 18 minutes.
Let cool completely then remove the cookies from the baking sheet.
Meanwhile, make the filling: Place the chopped chocolate in a bowl.
In a small saucepan, bring the heavy cream and corn syrup to a boil.
Remove the pan from the stove and pour the cream mixture over the chocolate and allow it to sit for 2 minutes. Stir the mixture until its well incorporated.
Add the butter pieces and stir until smooth. Allow to cool.
Assemble the macarons by spreading one cookie with filling and topping with another cookie. Repeat until all cookies are used.
50 grams powdered almonds, almond flour or almond meal
25 grams unsweetened Dutch-process cocoa powder
2 large egg whites, at room temperature
65 grams granulated sugar
4 oz. bittersweet or semisweet chocolate, finely chopped
½ cup heavy cream
2 tsp. light corn syrup
1 Tbsp. butter, cut into small pieces
This article appears in February 2011.