HEAT oven to 350°F.
COOK pasta as directed on package, omitting salt. Drain pasta, reserving 1/2 cup of the cooking water.
MIX spaghetti sauce, ricotta cheese and reserved cooking water in large bowl. Add pasta and 1/2 cup mozzarella; mix lightly. Spoon into 13x9-inch baking dish sprayed with cooking spray; sprinkle with remaining mozzarella and Parmesan. Cover.
BAKE 40 min. or until heated through, uncovering for the last 10 min.