Pre-heat the oven to 350°F.
Using a 13 x 9 x 2-inch casserole dish, place the bag of ravioli into the bottom of the dish; move around to distribute evenly.
Using a rubber spatula, evenly spread the ricotta cheese over the ravioli.
Cover the ricotta cheese layer with the marinara sauce; again, using a rubber spatula to evely distribute over the top.
Top the casserole with the mozarella cheese.
Place in the pre-heated oven and bake for 45 minutes.
Remove from the oven; change oven setting to broiler.
Place casserole dish under the broiler for 2 to 3 minutes; watch closely as the casserole could begin to burn very quickly.
