Weigh the egg whites in a small bowl and leave them out at room temperature for at least 1 hour to come to room temperature.
Prepare two baking sheets: Place your macaron templates onto 2 - large rimmed baking sheets with another sheet of parchment paper on top. You can lightly spray the template with non-stick spray so the top parchment paper sticks to it.
Have several clean and dry glass bowls ready and also clean and dry your food processor, sieve, spatula, whisk/mixers, and any other equipment you'll be using.
Use a sieve to sift the almond flour, powdered sugar, and granulated sugar, separately, and keep them in separate bowls.
After sifting, place a clean glass bowl on your food scale, set the scale to '0' (in grams), and weigh each of the ingredients, separately, and in separate bowls. Mix the almond flour and powdered sugar in one bowl, and add the sugar to the bowl of a food processor. Pulse the sugar in the food processor for about 5 seconds until it's a very fine texture.