Preheat oven to 375°F.
Layer the casserole:
Spread a thin layer of marinara on the bottom of a baking dish.
Add a layer of ravioli.
Spoon some sauce over the ravioli.
Add small dollops/pockets of ricotta throughout.
Sprinkle with mozzarella.
Repeat until everything is used up.
Finish with mozzarella on top.
Make sure all ravioli are covered with sauce so they don’t dry out.
Bake:
Cover with foil and bake for 25 minutes.
Remove the foil and bake for 10–15 more minutes, until the sauce is bubbling and the cheese is melted and lightly golden.
Rest for 5–10 minutes before serving.