- 3 cups gluten-free powdered sugar
- 3/4 cup unsweetened cocoa powder
- 1 teaspoon kosher salt
- 2 large egg whites
- 1 large egg
- 4 ounces bittersweet chocolate, chopped
- 3 tablespoons cacao nibs
- Place racks in lower and upper thirds of oven; preheat to 350°F. Whisk powdered sugar, cocoa powder, and salt in a large bowl, then whisk in egg whites and egg; fold in chocolate and cacao nibs. Spoon batter by the tablespoonful onto 2 parchment-lined baking sheets, spacing 2″ apart.
- Bake, rotating sheets once, until cookies are puffed, cracked, and set just around the edges, 14–16 minutes.
- Transfer baking sheets to wire racks and let cookies cool on pan (they’ll firm up).
- DO AHEAD: Cookies can be baked 3 days ahead. Store airtight at room temperature.