Heat oven to 375F.
Spoon a few tablespoons of tomato sauce into a 13x9 inch baking dish. Spread evenly to cover the bottom of the baking dish.
Lay ravioli on top of the sauce, creating a single layer of pasta (8 to 12 ravioli, depending on the size of your pasta).
Spread one third of the spinach and sliced mushrooms on top of the pasta. Sprinkle one third of the mozzarella cheese on top of the vegetables.
Continue layering sauce, ravioli, spinach, mushroom and cheese. Finish with a layer of Parmesan cheese.
Cover with aluminum foil and and bake for 30 minutes.
Remove foil cover and bake another 15 minutes.
Slice and serve immediately.
Enjoy!