Line 2 baking sheets with parchment paper or Silpat mats. Set aside.
Heat a small pot of water on medium-low heat until it begins to simmer. Set a heatproof bowl over the water. To the bowl, add the egg whites and granulated sugar. Whisk until the sugar has fully dissolved, about 2 minutes.
3 large egg whites, ½ cup granulated sugar
Transfer the egg and sugar mixture to the bowl of a stand mixer fitted with the whisk attachment. Beat on medium-high speed until stiff peaks form.
Use a mesh sieve to sift the powdered sugar and almond flour into the egg white meringue mixture. Discard any large lumps.
⅘ cup powdered sugar, 1 cup almond flour
Use a spatula to fold the dry ingredients into the meringue, making sure not to deflate them yet. Be gentle and make a "J" shape with your spatula, folding all the way to the bottom of the bowl.
Once the dry ingredients are incorporated, continue folding the meringue, this time pressing (smushing) the batter against the sides of the bowl. Continue to press and fold the meringue until you can draw an "8" without the stream breaking. This is known as the "ribbon" or "lava" stage.
Transfer the meringue to a piping bag fitted with a small round tip (Wilton #10 or #12). Pipe 1-inch macaron shells onto the prepared baking sheets, making sure to space them at least 2 inches apart.
Working with one baking sheet at a time, hold the sheet a few inches off the counter and drop it straight down onto the counter to remove air bubbles from the macarons. Repeat this 5-6 times.
Let the macarons rest for 25 minutes uncovered at room temperature, or until a skin develops.
While the macarons rest, preheat oven to 325°F.
Bake for 13 minutes, turning the tray halfway through baking.
Allow the macarons to completely cool before removing from the pan. (If removed when still warm they might stick).