Preheat oven to 275 degrees. Line 2 baking sheets with parchment paper or silicone baking mats.

If the maraschino cherries have stems, remove them. Dry them well with paper towels and let sit until ready to use.

Combine the egg whites with the cream of tartar, salt and vanilla in a mixer fitted with a whisk attachment. Start the mixer on low then increase the speed to high. When the egg whites are very foamy, add the sugar gradually while the machine is running. Continue to beat the egg whites until they form stiff, glossy peaks - about 5 minutes. Sift in the cocoa powder, fold gently to get them mixed in a little then mix on high speed with the mixer for a few more seconds until the cocoa powder is incorporated. You may have to scrape the side of the bowl a time or two.

Spoon 12 heaping tablespoons of the egg white mixture onto each prepared pan (a small #60 ice cream scoop works really well for this). Gently press a cherry into each mound of egg whites. Top with about a teaspoon of egg whites and, using an offset spatula or your fingers, seal the two meringue dollops together.

Bake for 2 hours, turn off the oven and let the cookies sit for 20 minutes - do not open the oven door. Peel the cookies off the parchment or silicone mats and serve. The cookies are best served within 24 hours, especially if you live in a humid climate. To store, put in an air proof container and keep at room temperature.

Alternately you can bake the cookies for 30 minutes at 300 degrees, let cool on a baking sheet and serve. They won’t really be crispy, but are still delicious.