Preheat the oven to 300°F (150°C) and line a baking sheet with parchment paper.

In a mixing bowl, sift together almond flour, powdered sugar, and cocoa powder.

In another bowl, whip the egg whites until foamy, then gradually add granulated sugar and whip until stiff peaks form.

Gently fold the dry ingredients into the egg whites until the batter flows like lava.

Transfer the batter to a piping bag and pipe small circles onto the prepared baking sheet.

Let the macarons sit at room temperature for 30 minutes to form a skin.

Bake in the preheated oven for 15 minutes, then let cool completely.

In a mixing bowl, beat the softened butter until creamy.

Gradually add powdered sugar and mix until combined.

Add heavy cream and crushed Oreo cookies, then mix until smooth.

Pair the macaron shells by size and spread or pipe the Oreo buttercream filling onto the flat side of one shell.

Top with another shell, pressing gently to adhere.

Refrigerate the assembled macarons for at least 24 hours to develop flavor.