Preheat your oven to 350 degrees Fahrenheit. Spray a 9x13 baking dish with non-stick cooking spray.
If you are making Homemade Marinara Sauce, you will want to do this in advance, it takes about 30 minutes. If you are using store-bought sauce, add it to a saucepan and heat through over low to medium heat.
While you are cooking the sauce, boil your ravioli according to the package instructions and drain when finished. Add salt and 1 tablespoon of olive oil to your pasta water so that it does not stick.
Add the cooked ravioli to the sauce and gently stir to combine. Transfer the saucy ravioli to the prepared baking dish.
Sprinkle the mozzarella over the ravioli in an even layer. Place on the center rack and bake for 20 - 25 minutes or until the cheese is melted and bubbly. (See notes.)
Once the ravioli is finished baking, carefully remove it from the oven and garnish with fresh chopped basil and parmesan cheese if desired. Serve hot and enjoy!