TIP: Precision is the key to successful macarons, so I suggest weighing all of your ingredients for the macarons instead of using cup measures.
1/2 cup heavy whipping cream, plus more as needed
4 ounces chocolate, finely chopped
125 grams almond meal
20 grams cocoa powder, plus more for dusting
200 grams confectioners' sugar
120 grams egg whites
80 grams granulated sugar
First, to make the ganache for the filling: In a medium saucepan, heat the cream to a simmer. Turn off the heat and add the chocolate, swirl the cream until it covers the chocolate, and allow to sit for 3 minutes, then gently whisk until smooth. If the ganache separates, whisk in a bit more cream until it comes together. Place in a bowl, cover with plastic wrap, and allow to come to room temperature while you make the macarons.
To make the macarons: In a food processor, pulse together the almond meal, cocoa powder, and confectioners’ sugar until it is well mixed and very fine. You may need to scrape down the sides.
In a stand mixer fitted with a whisk attachment, beat the egg whites until they are foamy. Sprinkle the granulated sugar over them in a steady stream and then turn up the speed and beat the whites until you’ve reached stiff peaks.
In three additions, you will now fold in the almond meal mixture using a rubber spatula. Once you have repeated this two more times with the remaining almond mixture, your batter will be quite thick. Here is a fail safe way of knowing when your batter is ready: first, press it up on the side of the bowl, and it will cling onto the sides without slumping into the middle. You want to continue folding the batter and repeat testing it on the side of the bowl, until it slumps down when you press it onto the sides of the bowl. Then you are ready to pipe.
Using a pastry bag fitted with a large round tip, pipe the batter onto a flat baking sheet lined with a piece of parchment paper. Once you have piped out a full tray, you will bang the tray on the counter to work out some of the bubbles and flatten the macarons. Repeat with another tray until all of the batter is used up. Let them sit at room temperature until the tops are dry to the touch, about 30 minutes, but it will depend on the environment.
While you are waiting, preheat your oven to 330°F.
Bake the trays one at a time for 10 minutes. If the macarons are not set, then rotate the tray and bake for an additional 2 to 3 minutes. This may be slightly different depending on your oven. Let them cool completely.
Place the room temperature ganache in a piping bag fitted with a small round or star tip. Try to match up same-sized shells and flip over one of each pair. Pipe the ganache onto the flipped shells. Macarons can be refrigerated in an airtight container for a few days. Dust with cocoa powder before serving.