• 1/2 to 3/4 c. filling, such as Nutella, jam, lemon curd, chocolate ganache or buttercream frosting
Cut 3 sheets of parchment paper to fit 2 baking sheets. With a marker and template (such as a large spool of thread) draw on 1 parchment a series of 24 to 28 circles measuring about 1 1/4-inch across, leaving an inch between each circle. Place this on baking sheet overlaid with a second piece of parchment. You should be able to see the circles through the paper.
Combine the powdered sugar and almond meal in a bowl and whisk together thoroughly. Then pass the mixture through a sifter or medium-coarse sieve (mesh size of 1/16 inch) to lighten it. Discard any almond bits left behind. (There may be none.) Set aside.
In a clear measuring cup, add enough egg whites to reach halfway between the 1/3 and 1/2 cup marks; or use a scale to weigh 3 3/4 ounces of egg whites. Transfer these to a large bowl and add cream of tartar. With a stand mixer or hand mixer, beat the egg whites at medium speed until they form soft peaks when beaters are lifted. Add the food coloring, if using. Resume beating, now at high speed while gradually adding the 3 tablespoons granulated sugar. Beat until the mixture forms stiff, but not dry, peaks when the beaters are lifted. A peak of egg white should stand straight up, with no drooping.
Pour one-third of the almond mixture over the egg whites and, with a large rubber spatula, fold into the egg whites to lighten them. Then add the remaining dry ingredients and continue folding until fully incorporated. (See related story below for the best folding technique.) The egg whites will deflate quite a bit, but the batter should look moist and glossy and slowly slide from the spatula.