Preheat your oven to 300°F (150°C) and line a baking sheet with parchment paper.
Sift together almond flour, powdered sugar, and matcha powder. Set aside.
In a mixing bowl, beat egg whites and a pinch of salt until foamy. Gradually add granulated sugar and beat until stiff peaks form.
Gently fold the dry ingredients into the egg whites until well combined and the batter flows like lava.
Transfer the batter to a piping bag and pipe small circles onto the prepared baking sheet. Tap the sheet on the counter to release air bubbles.
Let the macarons sit at room temperature for 30 minutes to form a skin.
Bake for 15 minutes. Let cool completely before removing from the baking sheet.
For the filling, beat the butter until creamy. Gradually add powdered sugar and matcha powder. Add milk and beat until smooth.
Pipe the filling onto half of the macarons and sandwich with the other halves.