Heat oven to 275°F. Line cookie sheet with cooking parchment paper or heavy brown paper. In medium bowl, beat egg whites and cream of tartar with electric mixer on high speed until foamy. Beat in 3/4 cup sugar, 1 tablespoon at a time; continue beating until stiff peaks form and mixture is glossy. Do not underbeat. On cookie sheet, shape meringue into 9-inch round with back of spoon, building up side.