Line an upside down pan with a silicone baking mat and fit a piping bag with a small #12 Wilton round tip, then set them both aside.
In a medium bowl, sift the almond meal, powdered sugar, and espresso into a larger bowl and discard any large pieces. Set aside.
In a stand mixing bowl, begin whisking the egg whites on medium low speed for 2-3 minutes until foamy, then add the cream of tartar.
Very slowly, sprinkle the sugar into the mixing whites with a spoon. When all of the sugar is added, increase the speed to medium and whip for about 7-8 minutes or until stiff peaks form.
Add ⅓ of the sifted dry mixture to the bowl of meringue. Fold very gently with a spatula until combined. Continue until all of the dry ingredients are incorporated, then add the food coloring.
Scrape the batter against the sides of the bowl. Every few scrapes, pick up the batter and let it fall into the bowl. The batter should flow slowly in a continuous ribbon. Try to make a figure 8 with the batter. If it falls without breaking, it's ready.
Pipe the batter in 1 ½ inch rounds (spaced 2 inches apart) directly over the baking tray. Drop the pan on the counter a few times to release any air bubbles which you can pop with a toothpick.
Let the shells sit to dry and form a skin, at least 30 minutes or until you can touch the tops without leaving an impression. Preheat the oven to 300 F/149 C.
Bake for 12-14 minutes. The shells are done baking when the top of the shell doesn't budge from the feet. Let the tray cool completely on a wire rack before removing the shells.