Move the oven rack to the middle position. Preheat oven to 225°F.
Line a large sheet pan with parchment paper.
MAKE MERINGUE:
Add the egg whites to the bowl of a stand mixer fitted with the whisk attachment. Beat on medium-high speed until the egg whites become foamy.
Add the cream of tartar.
Next, while the mixer is still at medium-high speed, slowly add the sugar, about one tablespoon at a time. Adding all of the sugar should take about two minutes.
Beat the egg whites until stiff peaks form.
Once the egg whites have reached stiff peaks, gently fold in the cocoa powder. Do not deflate the egg whites!
PIPE MERINGUE:
Transfer the mixture to a piping bag. Pipe small dollops (about 1” in diameter) that are at least an inch apart.
BAKE:
Bake the meringues for precisely one hour. Turn off the oven and slightly open the oven door, but leave the meringues inside! Allow them to cool slowly to room temperature.
SERVE AND STORE:
Once the meringues have cooled, serve them or store them in an airtight container at room temperature for up to three days.
Notes
Cream of tartar helps stabilize the egg whites and prevent cracking. This recipe cannot be made without it!
Use the highest-quality cocoa you can find. It’s the only meringue flavor, so you want it to be high-quality!
Once the meringues cool, you can dip or drizzle them with dark chocolate. Just allow the chocolate to fully set before storing.