Preheat oven to 200 F. Line two baking sheets with parchment paper.
Using the whisk attachment of a stand mixer, beat egg whites, vanilla, and cream of tartar until frothy.
Very very slowly add sugar.
Continue beating until the mixture is stiff and glossy.
Pipe or spoon mixture onto lined baking sheet.
Bake for 45 minutes, then turn off oven and let cookies sit in oven for an additional 30 minutes.
Remove and cool completely.