Preheat oven to 150°C (300°F). Line a baking sheet with parchment paper.
Sift almond flour and powdered sugar together.
In a mixing bowl, beat egg whites until foamy. Gradually add granulated sugar and beat until stiff peaks form.
Fold in the almond flour mixture into the egg whites. Add vanilla extract and food coloring if using.
Transfer the batter to a piping bag and pipe small circles onto the prepared baking sheet.
Tap the baking sheet on the counter to release any 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 butter until creamy. Gradually add powdered sugar, vanilla extract, and heavy cream. Beat until smooth.
Pipe the filling onto one macaron shell and sandwich with another shell.