Next, make the Italian macaron shells. Sift 160g almond meal and 160g powdered sugar into a large bowl.
Make a well in the center of the dry ingredients and pour in 60g of egg whites. Fold the mixture together until combined. Cover with plastic wrap and set aside.
Next, heat 160g granulated sugar and 40g water in a pot over medium heat with a candy thermometer attached to the side.
Heat over a medium heat and bring to a boil. As soon as the mixture starts to boil, pour the remaining 60g of egg whites in the bowl of a stand mixer and whisk on a medium speed.
Add in 1/4 tsp of cream of tartar to help stabilize the meringue and continue to mix at a medium speed until soft peaks form.
Continue cooking the sugar syrup until it reaches 238°F/114C°. Then slowly pour the syrup between the edge of the bowl and the whisk attachment while mixing on a medium speed. The syrup might splatter a bit around the bowl as you pour, but that's ok! Just do your best to avoid having the syrup hit the whisk attachment.
Once the syrup is fully mixed in, increase the mixing speed to a high speed and mix until glossy, stiff peaks form (this usually takes me 6-7 minutes). There should be a tiny bend in the peak of your meringue when the whisk is lifted. If you want to color your macarons, mix in the gel food coloring during this step. Then mix the meringue into the almond/powdered sugar mixture in two additions.
Once the meringue is mixed in, fold the batter in a circular motion until thick ribbons of batter run off the spatula when it is lifted. Be careful not to over-mix the batter!
Transfer batter to a large piping bag fit with a medium sized round piping tip and pipe 1 1/2-inch rounds on baking sheets lined with silpat mats, spacing them about 1 inch apart.
Bang the pans firmly on the counter a few times to release air bubbles, then pop any remaining air bubbles that come to the surface with a toothpick.
Preheat the oven to 320°F/160°C, then let the macarons rest for 30 minutes to allow a skin to form. They should look matte and be dry to the touch once they're ready to be baked.
Bake one tray of macarons at a time on the middle rack of your oven for 16-20 minutes.
Remove from oven and let the macarons cool fully on the pan, then gently remove them from the silpat mat.