Preheat oven to 120ºC. Line a small baking sheet with parchment paper.

In a small bowl, sift or whisk together sugar, 1 tablespoon cocoa and cornstarch; set aside.

In a medium bowl, combine the egg white and cream of tartar. Beat with an electric mixer at medium-high speed until foamy, about 1 minute. Increase mixer speed to high and gradually add sugar mixture to egg white, 1 teaspoon at a time, until stiff peaks form, 4–5 minutes.

Spoon half of egg white mixture onto the prepared baking sheet, shaping into a 3 1/2– 4-inch nest. Repeat with the remaining egg white mixture. Bake until firm and dry to the touch, 35–40 minutes.

Turn oven off, but leave the pan inside. Allow meringues to cool in the oven for 1 hour.

Combine yogurt and remaining 1 tablespoon cocoa. Divide yogurt mixture evenly between meringues and top with raspberries.