HEAT oven to 225ºF.
BEAT egg whites and cream of tartar in medium bowl with mixer on high speed 5 min. or until soft peaks form. Add granulated sugar, 1 Tbsp. at a time, beating until stiff peaks form.
SPREAD into 10-inch circle on parchment-covered baking sheet, indenting center slightly. Bake 1-1/2 hours. Cool.
MEANWHILE, beat pudding mix and milk in medium bowl with whisk 2 min. Stir in COOL WHIP. Refrigerate 15 min. Place meringue on plate; fill center with pudding mixture. Top with berries and powdered sugar.