In a medium bowl, mix the sifted almond flour and powdered sugar.
In a small bowl, combine granulated sugar and cream of tartar.
Pour the egg whites into the bowl of a stand mixer. Set up a stopwatch to time how long to whip the meringue. (These times are listed to help beginner macaron makers. With practice, you can go by eye.)0:00 - 4:00 minutes: Mix on medium-low for 4 minutes (Kitchenaid speed 4).4:00 - 9:30 minutes: Turn the mixer to medium speed (Kitchenaid speed 6). Add a third of the granulated sugar and cream of tartar mixture. After 30 seconds, add another third. After another 30 seconds, add the last of the granulated sugar and cream of tartar mixture. Keep mixing at medium speed until you have reached a total of 9:30 minutes. The meringue should be balled up onto the whisk, very thick, glossy, and have stiff peaks. If not, keep mixing at 30-second intervals at Kitchenaid speed 8 until it is. Add all of the powdered sugar, almond flour, and a SMALL amount of purple food coloring to the meringue. I like to use a cake tester or knife, get a bit of purple food coloring on it, and scrape it into the meringue. The purple offsets the yellow color from the almond flour, making your batter white.Gently fold the macaron batter, often scraping the sides and bottom of the bowl. Continue folding, adding more purple food coloring as needed.
Fold the batter until it reaches a thick, glossy consistency and flows off the rubber spatula into ribbons. To test if it is ready, allow the batter to flow off the spatula and into the batter. If the ribbons do not melt into the rest of the batter after 30 seconds, continue folding. Be careful not to over mix. When it passes this test, transfer a little more than 3/4 of the batter to your medium piping bag, and the remaining to your small piping bag.
With your medium piping bag, pipe round shells onto your silicone mats/parchment paper, using the round macaron template as a guide. Tap the trays against the counter a few times to get rid of air bubbles. If there are bubbles on the surface, you can use a toothpick or cookie scribe to pop them. Popping the air bubbles helps stop them from cracking when being baked.
Once you get rid of as many air bubbles as possible, you will now pipe the ears with the smaller tipped bag. You can pipe ears on half of the macaron shells or all of them—it is your preference. Using the small piping bag, pipe a small circle on the top left of on of the shells to make one of the ears. Repeat on the top right side for the other ear.
Allow the macarons to sit out at room temperature to dry for at least one hour. They will be ready to bake once the surface of the macaron is matte and dry to the touch. If it is a really humid day, it can sometimes take 2 hours for them to dry.
Preheat the oven to 325F. Place an empty baking sheet upside-down on the middle rack.
Place the baking sheet with the macarons on top of the upside-down baking sheet. Bake for 15-20 minutes, rotating halfway through. To test if they are done baking, gently push the side of one shell. If it wiggles on the sheet, they need to be baked longer.
Remove the macarons and place them on a wire rack. Bake any remaining macaron shells.
Allow macarons to fully cool before peeling them off the parchment paper or silicone mats.