Sift together almond flour and powdered sugar into a bowl. In a separate bowl, whip egg whites until foamy, then add granulated sugar gradually until stiff peaks form. Fold in dry ingredients and food coloring gently.

Line a baking sheet with silicone mat or parchment paper. Transfer batter to piping bag and pipe small rounds, about 1.5 inches wide.

Let piped macarons sit at room temperature for 30 to 60 minutes until tops are dry to the touch.

Preheat oven to 300°F (150°C). Bake shells for about 15-20 minutes until edges are firm.

Cool macarons on the baking sheet for 10 minutes, then transfer to wire rack. Pair shells and fill with buttercream.