In the mixing bowl sift together almond flour and powdered sugar. Set aside.
In the mixing bowl of stand mixer add room temperature egg whites and start whisking on low speed. Start adding sugar one tablespoon at the time. Add food coloring. Increase speed to medium-high and whip until stiff picks. This will take 10-15 minutes.
Add dry ingredients and start folding the butter. When macaronage drips down from the spatula “like lava”, transfer into pipping bag with round tip.
Pipe macaron shells on the baking mat.
Top baking sheet pan with pipped macaron shells a few times. Let shells to rest on the countertop until no batter sticks to your finger when you touch.
Bake macaron shells in the preheated oven to 275o F (134o C) for 12-14 minutes. Oven temperature and baking time may vary, depending on your oven.
Remove baked macaron shells from the oven and let it cool on the baking mat with baking sheet pan. When shells are cooled completely remove from baking mat and pair them with similar size.