For the Macaron Shells:

1. 1. Preheat your oven to 300°F (150°C) and line two baking sheets with parchment paper.
2. 2. Sift together almond flour, icing sugar, cocoa powder, and salt in a bowl to ensure a fine texture.
3. 3. In a clean mixing bowl, whip egg whites until foamy. Gradually add granulated sugar while continuing to whip until stiff peaks form.
4. 4. Gently fold the dry mixture into the whipped egg whites using a spatula until the batter flows like lava.
5. 5. Transfer the batter into a piping bag fitted with a round tip and pipe small circles onto prepared baking sheets, spaced about an inch apart.
6. 6. Let the piped macarons rest for 30 minutes to form a skin before baking.
7. 7. Bake each tray separately for about 15-20 minutes or until they easily lift off the parchment without sticking. Cool completely.

For the Ganache Filling:

1. 1. Melt dark chocolate and butter together in a microwave-safe bowl until smooth and creamy.
2. 2. Allow it to cool slightly before piping onto half of your macaron shells, then sandwich them with another shell.