Using a blender, finely blend the powdered sugar, almond flour and powdered food coloring. Use a sieve to sift out any large pieces of almond remaining and toss them out. Transfer the dry ingredients to a large bowl.
In the bowl of a spotless stand mixer (or in a large clean bowl if using a handheld mixer), beat the egg white on high speed until it is frothy. Add in the granulated sugar and continue to beat on high speed until you reach stiff peaks. The egg white mixture should be very smooth and shiny.
Turn off the mixer and slowly transfer the dry ingredients into the egg white mixture. Using a rubber spatula, gently fold the dry ingredients and use no more than 60 strokes. Your macaron shell mixture is ready once you lift your spatula and the mixture falls back onto itself like lava.
Transfer the mixture to a piping bag fitted with a medium-sized round tip (if you don't have a piping bag, use a ziploc bag with the end snipped off).
Line a baking sheet with parchment paper or a silicone baking mat. Gently squeeze out some batter from the piping bag onto the lined baking sheet in a vertical motion. Pipe until the batter forms a circle about 1/2" to 1" in diameter. Pipe the remaining circles on the sheet.
Lift the baking pan up and rap on the counter several times to get the air bubbles out. Allow the tray to rest at room temperature for about 30 minutes.
Preheat your oven to 300 degrees F. Bake the macarons for 12 minutes and allow the shells to cool before removing from the baking pan.