Place the egg whites into the bowl of a stand mixer fitted with a whisk attachment. Let sit at room temperature for 30 minutes.
3 large egg whites
Meanwhile, in medium size bowl, sift together the sugar, cream of tartar and salt. Discard any large pieces of sugar left. Set bowl aside.
60 grams granulated sugar, ¼ teaspoon cream of tartar, ⅛ teaspoon fine sea salt
In a separate large bowl, sift together the powdered sugar, almond flour, cocoa powder and instant espresso. Process the remaining large pieces in a food processor to pulverize them, then sift. Set the bowl aside.
150 grams confectioners' sugar, 120 grams almond flour, finely ground, 2 tablespoons cocoa powder, Dutch, ¾ teaspoon instant espresso or coffee
Line half baking sheets with parchment paper, or macaron guide silicone mats. Or place macaron templates under the parchment, if using.
Beat the egg whites on medium speed until foamy.
Beat in the granulated sugar, cream of tartar and salt mixture.
Whip the egg white mixture until stiff peaks form. The meringue will stand up straight when the whisk is removed. The egg white mixture will be thick and glossy.
Remove the bowl from the stand mixer and fold in the almond flour mixture. The egg whites will deflate a bit and that is ok. The batter is ready when it "ribbons", when falls off the spatula in a steady stream. You should be able to make a "8" with the batter falling off the spatula. This means the batter is ready. You're looking for about 65-75 folds. Check for the ribboning after every 10-15 folds.
Fill a piping bag fitted with a round tip (Wilton 1A or 2A) and pipe 1 ½" rounds on the parchment paper.
Firmly tap the pans on the counter 2-3 times to remove air bubbles. Let the macarons sit until just slightly tacky, but no batter comes off on your fingers, about 30-45 minutes.
Meanwhile preheat the oven to 300F. Bake the macarons for 20 minutes. Rotate the pans halfway through baking. Cool completely.