Nutella Ganache

1. Break or finely chop the milk chocolate and place it in a heatproof bowl with the Nutella.
2. Heat half of the heavy cream in a saucepan over medium heat until it begins to simmer.
3. Pour the hot cream over the chocolate and Nutella, and let it sit for a moment before stirring with a spatula until you achieve a smooth ganache.
4. Then, add the other half of the cold cream and mix it in.
5. Use an immersion blender if needed to further smooth the ganache.
6. Cover with plastic wrap directly touching the surface and refrigerate for approximately 3-4 hours.

Chocolate macaron Shells

1. Mix the dry ingredients - almond flour, powdered sugar, and unsweetened cocoa powder - in a food processor, then transfer them to a medium bowl.
2. In the bowl of a stand mixer fitted with the whisk attachment, place the room-temperature egg whites.
3. Whip at medium speed until they become frothy.
4. While continuing to mix at a slow to medium speed, add the granulated sugar one tablespoon at a time, allowing approximately 30 seconds to 1 minute between each addition.
5. Then, increase the speed to high and whip for 5-10 minutes until you achieve stiff peaks.
6. Pour the dry mixture all at once onto the meringue and gently fold it in using a spatula, making circular motions until you have a homogeneous mixture and the batter falls off the spatula in a ribbon-like manner when lifted.

Baking

1. Preheat the oven to 140°C (284°F) and prepare 2-3 baking sheets lined with parchment paper or special macaron silicone baking mats.
2. Transfer the macaron mixture into a large pastry bag fitted with a 10 mm round tip.
3. Pipe mounds of batter onto the baking sheet, leaving enough space between them.
4. Allow the piped macarons to dry for approximately 10-15 minutes in a dry place (until you can touch them with your finger without them sticking).
5. Bake the macarons in the middle of the oven for about 14 minutes (rotate the sheet halfway through baking if the shells don't rise evenly).
6. Let the shells cool slightly before gently removing them.

Assemble

1. Remove the cold ganache from the fridge and whip it for a maximum of one minute using an electric mixer to slightly firm up its texture.
2. Transfer the Nutella ganache into a large pastry bag and fill the center of one macaron shell. Add a little Nutella spread to the center using a second pastry bag, and then sandwich with another macaron shell.
3. Place the Nutella macarons in an airtight container in the refrigerator for 1 hour before enjoying them.