Preheat the oven to 300 degrees F (150 degrees C). Line two baking sheets with parchment paper.
Sift together the almond flour and powdered sugar
Using the standing mixer, whisk the egg whites until foamy. Then add the cream of tartar and VERY gradually add the sugar until stiff peaks form.
Add the food coloring and vanilla to the egg white mixture, if desired.
Gently fold the almond flour mixture, 1/3 at a time, into the egg white mixture until just combined. It should have a ribbon-like consistency.
Transfer the macaron batter to a piping bag fitted with a medium round tip. Glue down the parchment paper to the sheet pan by piping a little bit of batter under the paper.
Pipe the macaron batter onto the prepared baking sheets in 1” circles, spacing them about 1 inch apart.
Tap the baking sheets on the counter a few times to remove any air bubbles.
Let the macarons sit at room temperature for 30-40 minutes, or until they form a skin.
Bake the macarons for 12-15 minutes, or until they are set and dry.
Let the macarons cool completely on the baking sheets before removing them.