Combine almond flour and powdered sugar into the bowl of a food processor. Turn on high for 2 - 3 minutes until almond flour is fine. Sift the flour and sugar together into a large bowl.
If there are any pieces of almond flour left, process again until fine. You don’t want to have any more than 3 T of almond flour left in the sifter, which you can discard. Set aside.
Add the egg whites into the bowl of a stand mixer fitted with the whisk attachment. Add the cream of tartar. Turn on medium-high.
Once the whites are frothy, slowly add the granulated sugar. Continue to whisk until stiff peaks form. When you take out the whisk, the egg whites should stand completely straight, and not fall over to the side at all. This is the meringue.
Put a drop of gel food coloring in the meringue. Slowly add flour mixture in three separate batches. Fold flour into the meringue. Once all the flour has been added, the color should be completely distributed throughout the batter.
Add batter to a piping bag and cut the bottom, leaving a 3/4" hole to pipe. Gently pipe the batter (forming a circular cookie) onto the parchment paper template. Let them sit for 20 - 30 minutes until dry. Lightly touch a cookie and if it’s slightly hardened and not tacky, they are ready to bake.
Bake at 350 for 6 minutes, then rotate the cookie sheet and bake for an additional 6 minutes. You may need an additional 3 or so minutes. Remove from the parchment paper and allow to cool completely before adding filling.