Preheat oven to 350ºF (180ºC).
In a medium bowl, sift together almond flour, powdered sugar, and cocoa powder.
In a large bowl, beat the egg whites on medium speed until foamy.
Slowly add sugar one tablespoon at a time.
Increase the speed to medium-high and beat until hard peaks form.
Fold the dry ingredients, in two batches, into the beaten egg whites with a rubber spatula.
Pour the batter into a pastry bag.
Pipe about a spoonful of batter onto the baking paper at regular intervals. Set aside for 15 minutes.
Bake the macarons in the oven for 13 minutes. Remove from the oven and cool.
In a small saucepan heat the cream.
When the cream just begins to boil at the edges, remove from heat and pour over the chopped chocolate.Stir in the butter.
Cool the ganache in the fridge to thicken.
Add a teaspoon of chocolate filling on the flat side of a macaron, take a second macaron and put it on the filling.