To prepare the macaron filling, first put the chopped chocolate and unsalted butter together in a bowl.
Then, heat the heavy whipping cream to a boil, and pour it into the bowl with the chocolate and butter. Mix together until smooth, and store for 1 hour in the refrigerator, or until the ganache reaches a firm texture.
To prepare the macaron shells, in a large bowl, combine the almond powder, powdered sugar, cacao powder, and 2 1/2 egg whites. Mix with a stiff wooden spatula until almond paste is formed. Then, set aside.
Using a stand mixer, add 2 1/2 egg whites to a bowl, and mix on medium speed with the whisk attachment until the egg whites look fluffy and have doubled in volume.
Heat the sugar and water in a saucepan on medium heat until the mixture is 244 F.
Once the temperature is reached, pour the sugar syrup into the fluffy egg whites all at once (while stand mixer is on medium speed), then put the stand mixer on high speed for 5 minutes, or until stand mixer bowl is no longer hot.
Combine the meringue and almond paste by dividing the meringue into 3 separate parts and adding 1/3 at a time. Make sure the first 1/3 of meringue is well incorporated into the almond paste before adding the second 1/3 of meringue. For the final 1/3 of the meringue, use a rubber spatula, and fold it into the almond paste.
Fill a piping bag with a round tip with the macaron batter.
Preheat oven to 320 F.
Pipe the macarons on a silicon mat, making sure they are 1 inch apart.
Once the macarons are pipped, lightly tap the baking tray on the counter to get rid of air bubbles.
Bake at 320 F for 12 to 15 minutes, depending on the size of the macarons.
Once baked, allow the macarons to cool for 10 minute before scrapping them off the silicone mat.
Pair up macarons, and fill with ganache using piping bag with round tip.
Store in refrigerator for 6 hours minimum before eating.