(Yields about 30 2-inch cookies)
These flourless cookies are like a cross between macarons and meringues, with a crisp outer shell and moist, gooey dark-chocolate interior.
Position oven racks in the upper and lower third of the oven, and heat the oven to 350ºF. Line two cookie sheets with If You Care parchment baking paper.
Melt the chocolate, either in a metal bowl set over a pan of simmering water, or in the microwave in 30-second bursts, stirring after each interval. Set aside.
With a hand mixer or whisk attachment in a stand mixer, whip the egg whites, vanilla extract, and cream of tartar until soft peaks form. With the mixer running, gradually add the sugar and espresso powder until the egg whites form stiff peaks.
Pour the melted chocolate and almond meal over the egg whites and, using a silicone spatula, gently fold everything together until just incorporated (there should be no streaks of egg white).
Scoop scant tablespoons of the batter onto the prepared baking sheets, at least 1 inch apart. Bake until the cookies are cracked and look dry on the outside, but still feel soft inside, 10 to 12 minutes.
Transfer the parchment sheets to racks to cool. The cookies are best served the day they’re made, but will keep in a covered container for a couple days.