Beat eggs, cream of tartar and salt in medium bowl with electric mixer on high speed until foamy. Beat in sugar, 1 tablespoon at a time; continue beating until stiff and glossy (do not underbeat). Whisk in vanilla. Drop meringue in 6 evenly sized mounds onto a parchment-lined baking sheet. Shape into circles, building up sides. Bake in a preheated 350° oven 20 min. until a cake tester inserted in the center of a meringue comes out clean.