Space 2 racks evenly in the middle of the oven and preheat to 350°F (180°F). Line 2 baking sheets with parchment paper.
In a clean, dry, heatproof bowl, whisk together the egg whites and sugar. Set over (but not touching) simmering water in a saucepan. Whisk constantly until the sugar is completely dissolved. Remove from the heat.
Using a mixer fitted with the whip attachment, beat the eggs on high speed until stiff and glossy. Sift the cocoa over the meringue. Sprinkle with the chocolate and the cocoa nibs, then fold together gently with a rubber spatula until combined.
Drop the meringue by heaping tablespoons, spaced slightly apart, onto the prepared baking sheets. Bake for 9 minutes. Rotate the pans and bake until the cookies are fluffy, full of cracks, and spring back when touched, about 9 minutes. Carefully pick up the parchment sheets and transfer the cookies, still on the parchment, to wire racks to cool.
This meringues recipe is excerpted with permission from <a href="http://www.amazon.com/gp/product/1616282002/ref=as_li_qf_sp_asin_il_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=1616282002&linkCode=as2&tag=craftfocom-20">"Home Baked Comfort (Williams-Sonoma): Featuring Mouthwatering Recipes and Tales of the Sweet Life with Favorites from Bakers Across the Country"</a> by Kim Laidlaw and published by Weldon Owen.