Preheat oven to 300°F. Sift almond flour and powdered sugar twice for a smooth base.

In a clean bowl, whip egg whites until foamy, then gradually add granulated sugar.

Gently fold the almond flour mixture into the whipped egg whites until the batter flows like molten lava.

Pipe 1.5-inch circles onto parchment-lined sheets and tap gently to release air bubbles.

Let the piped macarons rest at room temperature for 30-60 minutes until a skin forms.

Bake the rested macarons for 15-18 minutes, rotating halfway for even baking.

While cooling, cream butter, slowly adding powdered sugar, then vanilla and milk until creamy.

Match macaron shells, pipe buttercream onto one, and sandwich it with another shell.