Line two large sheet pans with parchment paper or Silpat mats. Set aside.
Place a heatproof bowl over a small saucepan of simmering water. Add the egg whites and granulated sugar to the bowl. Whisk until the sugar has fully dissolved, about 2 minutes.
3 large egg whites, ½ cup granulated sugar
Transfer the mixture to the bowl of a stand mixer fitted with the whisk attachment. Beat the egg whites and sugar on medium-high speed until they form stiff peaks, about 3-4 minutes.
Use a fine mesh sieve to sift the powdered sugar and almond flour into the egg whites. Make sure to discard any large lumps; don’t force them through the sieve.
⅘ cup powdered sugar, 1 cup almond flour
Gently fold the dry ingredients into the egg whites by making a "J" shape with your spatula. Make sure to scrape all the way to the bottom of the bowl!
Once the dry ingredients have been almost fully incorporated, add the gel food coloring, if using (see notes).
Gel food coloring
Continue folding, this time gently smushing the meringue against the sides of the bowl as you fold. Smush and fold a few times before checking to see if the meringue is at the Figure 8 stage.
If you can draw an 8 with the meringue without the stream breaking, it’s ready to pipe. If it falls off in clumps, continue the smush and folding a few more times before trying again.
When the meringue flows in smooth ribbons, transfer it to a piping bag fitted with a small round tip (Wilton #10 or 12).
Pipe either circles or egg shapes that are about 1 inch in diameter. Once you’ve finished the first tray, hold it a few inches off the counter and drop it straight down to release any air bubbles. Repeat a few times, or until it looks like any large air bubbles have popped.
Repeat with the second tray.
Set the trays aside to rest for 25-30 minutes, or until they have developed a skin. On humid days, this could take up to an hour. When the macarons are ready to bake, you should be able to touch the macarons gently without the meringue sticking to your finger.
While the macarons rest, preheat your oven to 325°F.
Bake the macarons, one tray at a time, for 13 minutes. Make sure to turn the tray half way through cooking so the feet rise evenly.
Allow the macarons to cool fully on the tray. Trying to remove the macarons while they’re warm may result in sticking.