Sift the powdered sugar and almond flour together.
Using a hand mixer, whip the egg whites on low speed until frothy. Gradually add the sugar, and then whip on high speed until stiff peaks form. The egg whites should be glossy and thick.
Fold half of the almond mixture into the egg whites and then add the rest. Fold the mixture 15 to 20 times; the batter will be thick and fall slowly when dripped from the spatula.
Pipe 1-inch circles onto baking sheets lined with silicon mats or parchment paper. Let rest until a skin forms on top and is dry to the touch, 15 to 30 minutes.
Preheat the oven to 350 degrees F.
Bake for 10 to 12 minutes, rotating the pans halfway through the baking time. If you are baking two sheets at a time, the bottom and top sheets should be rotated to prevent over browning on the bottom. If only baking one sheet at a time, bake on the bottom rack first for 5 minutes with an empty sheet on top. After 5 minutes, rotate the sheet and move the bottom sheet to the top and the top sheet to the bottom.
You will know the macarons are done when you can touch them and the top of the macaron is set does not slide around under your finger. The macarons must be set before you take them out of the oven. If the macaron tops slide, put them back in the oven on the middle rack for another 2 minutes.
Let them cool for about 10 minutes on the baking sheet and then take them off. Fill as desired with your favorite chocolate ganache, jams, or whatever creative fillings you can think of!