It’s important to let the piped dough stand for 1 hour before baking; otherwise, the tops will crack. Sprinkling the dough with sanding sugar before baking gives these cookies an attractive sparkle.
Sift the confectioner’s sugar into a large bowl. Whisk in the almond flour. In a clean, large bowl, using an electric mixer on medium-high speed, beat the egg whites until they form a dense foam, about 1 minute. Add the salt. Beating continuously, gradually add the granulated sugar. Beat until stiff, glossy peaks form, 3–4 minutes. Add 1 or 2 drops of the food coloring t