Preheat the oven to 170 degrees F and line baking sheets with parchment paper. Whip the egg whites on high speed, gradually adding the sugar, then the cream of tartar and vanilla, until stiff, glossy peaks form.
Transfer the meringue to a piping bag fitted with an open star tip. Pipe 1 inch swirls about 1 inch apart on the lined sheets and decorate with sprinkles if desired.
Bake for 2 hours, then turn off the oven and let the meringues cool inside for about 1 hour. Serve and enjoy.