Add the almond flour and powdered sugar to a food processor and pulse several times.
Sift the mixture through a fine mesh sieve into a large bowl.
Discard any large pieces that remain.
Add the egg whites to a clean mixing bowl.
Beat on medium speed until foamy.
Add the cream of tartar.
Slowly add the granulated sugar while continuing to beat.
Beat until stiff glossy peaks form.
Mix in the vanilla extract and food coloring if using.
Add one-third of the almond flour mixture to the meringue.
Fold gently using a spatula until mostly incorporated.
Add another third and continue folding.
Add the final third and continue folding until the batter flows like lava.
The batter should ribbon from the spatula and disappear back into itself within 10–15 seconds.
Transfer batter to a piping bag fitted with a round tip.
Pipe 1½-inch circles onto parchment-lined baking sheets.
Tap the baking sheet firmly several times on the counter to remove air bubbles.
Pop any visible bubbles with a toothpick.
Let the macarons rest for 30–60 minutes until the tops feel dry to the touch.
Preheat oven to 300°F.
Bake for 14–16 minutes.
Macarons are done when they have developed feet and no longer wobble when touched.
Cool completely before removing from the parchment paper.