2largeegg whitesat room temperature, left to sit out on the counter overnight
5tablespoons (65 grams)granulated sugar
1/2cupheavy whipping cream
5ouncesbittersweet or semisweet chocolatefinely chopped
2tablespoonsbuttercut into small pieces
Preheat oven to 350°F (176°C). Line two baking sheets with parchment paper or silicon mats. Prepare a pastry bag with a plain round tip (about 1/2-inch) so it's ready to go.
Use a food processor to grind together the powdered sugar, almond flour, and cocoa so there are no lumps. Pulse a five or six times to make sure the almond flouf is finely ground.
In the bowl of an electric mixer, beat the egg whites until soft peaks form. Without stopping the mixer, beat in the granulated sugar until the peaks are stiff and firm, about 2 minutes.
Carefully fold the dry ingredients, in two batches, into the beaten egg whites with a flexible rubber spatula. Be very careful not to over mix and flatten the whites. When the mixture is just smooth and there are no large streaks of egg white, stop folding. Gently scrape the macaron batter into the pastry bag.
Pipe the batter on the lined baking sheets in 1-inch circles (about 1 tablespoon each of batter), evenly spaced one-inch apart.
Drop the baking sheet on the counter a few times to flatten the macarons and release any large bubbles (if you see any bubbles, pop them quickly with a toothpick). Allow macarons to sit on the counter, uncovered, for 30 minutes. Bake them for 15-18 minutes. Let cool completely before removing from baking sheet.
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.
To assemble, spread 2 teaspoons of filling onto the flat side of half of the macaron shells. Sandwich the filling with another shell. Seal the macarons in a plastic container and refrigerate them overnight, allowing the flavor and texture to mature. Enjoy cold or at room temperature.