- 2 (about 20-oz. each) bags square ravioli
- 2 (24-oz.) jars spaghetti sauce, divided
- 3 Tbsp. grated Parmesan cheese, divided
- 1 (9-oz.) box frozen spinach, thawed and drained (optional)
- 3 cups (12-oz.) shredded mozzarella cheese, divided
- Preheat oven to 350 degrees F.
- In a large pot of boiling salted water, cook ravioli for 4 minutes; drain.
- In a 9- x 13-inch baking dish, place 1-1/2 cups spaghetti sauce; layer 1/3 of the ravioli over sauce, sprinkle with 1 tablespoon Parmesan cheese, and 1/3 of the spinach, if desired.
- Pour 1-1/2 cups sauce over spinach, then cover with 1 cup mozzarella cheese.
- Repeat layers two more times with everything except final layer of mozzarella cheese, ending with sauce on top.
- Bake 30 minutes, remove from oven, sprinkle with remaining mozzarella cheese, return to oven for 5 to 10 minutes more or until heated through and cheese is melted.