|1 cup 3 tbsp dutch-process cocoa powder|
|3 cups confectioners’ sugar|
|2 3/4 walnuts - chopped • toasted|
|4 egg whites • at room temperature|
|1 tbsp pure vanilla extract|
Place a rack each in the upper and bottom thirds of the oven and preheat the oven to 350°F. Line two baking sheets with parchment paper or silicone baking mats.
Combine the cocoa powder, confectioners’ sugar, salt, and walnuts in the bowl of an electric mixer fitted with the paddle attachment. Mix on low speed for 1 minute.
With the mixer running, slowly add the egg whites and vanilla. Mix on medium speed for 3 minutes, until the mixture has slightly thickened. Do not overmix it, or the egg whites will thicken too much.
With a 2-ounce cookie or ice cream scoop or a generous tablespoon, scoop the batter onto the prepared baking sheet, to make cookies that are 4 inches in diameter. Scoop 5 cookies on each pan, about 3 inches apart so that they don’t stick when they spread. If you have extra batter, wait until the first batch of cookies is baked before scooping the next batch.
Put the cookies in the oven, and immediately lower the temperature to 320°F. Bake for 14 to 16 minutes, or until small thin cracks appear on the surface of the cookies. Switch the pans halfway through baking. Pull the parchment paper with the cookies onto a wire cooling rack, and let cool completely before removing the cookies from the paper. Store in an airtight container for up to 2 days.