Instructions

• Preheat the oven to 225°F. Place a sheet of parchment paper on a baking sheet, use a 9-inch cake pan to trace a 9-inch circle on the parchment, then flip the parchment over so the traced side is facing down on the baking sheet.
• Ensure the mixing bowl and whisk/whip attachment are clean and dry. Add 4 room-temperature egg whites, 1/8 teaspoon cream of tartar, and 1/8 teaspoon salt to the bowl.
• Fit the mixer with the whip attachment and beat the egg-white mixture on high until soft peaks form, about 45–50 seconds.
• With the mixer still on high, gradually add 1 cup of the sugar in a slow, steady stream. Continue beating until the mixture holds stiff, glossy peaks, about 1½ minutes.
• Remove the bowl from the mixer. Sift 2 tablespoons cocoa powder over the meringue, add the remaining 1/4 cup sugar and 1 tablespoon cornstarch, and gently fold everything together with a rubber spatula until uniform and no streaks remain.
• Spoon or pipe the meringue onto the traced circle on the parchment, leaving a 1/8–1/4-inch gap from the traced edge. Use an offset spatula to smooth the top and straighten the sides.
• Bake the meringue in the preheated oven for 15 minutes at 225°F. Immediately reduce the oven temperature to 200°F and continue baking for 2 hours and 45 minutes.
• Remove the baking sheet from the oven and let the meringue cool on the sheet for 45 minutes before handling or transferring.