PREHEAT oven to 375 degrees F.
HEAT marinara sauce and water to a low simmer.
ADD tortellini to a 13” x 9” baking plan or casserole, add marinara sauce mixture and meatballs and toss to combine.
TOP with mozzarella cheese and cover with aluminum foil.
BAKE for 10 minutes; remove foil and bake an additional 8 minutes. If more browning is desired, place under the broiler until cheese is golden brown.
Serve warm and, if using, top with chopped parsley.
