Preheat oven to 250°F. Beat egg whites, vanilla, vinegar, water, salt and baking powder in large bowl with electric mixer on medium speed until soft peaks form. Gradually add sugar, beating until stiff peaks form. Draw 2 (9-inch) circles on foil-covered large baking sheet. Spray with cooking spray. Spoon meringue onto circles; spread to edges of circles (they may overlap slightly). Bake 1 hour or until meringues are lightly browned. Cool completely on wire racks.