Combine almond flour, powdered sugar, and cocoa powder in a food processor and blend for 30 seconds. Sift into a bowl.

Whip egg whites on medium speed until soft peaks form, add granulated sugar gradually, and whip until glossy and stiff peaks form.

Fold the sifted dry ingredients into the meringue until the batter flows like a thick ribbon.

Pipe the batter onto a lined baking sheet into evenly sized rounds, about 3 cm in diameter.

Let the shells rest until they form a dry skin, about 15-30 minutes. Preheat the oven to 140°C (285°F) and bake for 14-16 minutes.

Heat heavy cream until simmering, pour over chopped milk chocolate and Nutella, stir until smooth, then chill for 1 hour.

Assemble macarons by piping ganache on one shell, adding Nutella, and sandwiching another shell on top.

Refrigerate assembled macarons for at least 1 hour before serving for best flavor.