Set a skillet over medium heat. Add some olive oil, the mushrooms, kosher salt, and pepper. Cook 3 to 4 minutes. Add the spinach, garlic, more kosher salt, and pepper and cook another 3 to 4 minutes.

Note: You may need to add the spinach in two batches, it will cook down a lot after a minute or two.

Brush a 9x13 casserole dish with olive oil and spread a few spoonfuls of the marinara sauce.

Place a single layer of ravioli in the bottom, add half of the veggie mixture, some mozzarella, more marinara sauce, drizzle half of the heavy cream, kosher salt, and pepper. Place another layer of ravioli and repeat with the rest of the veggies, more mozzarella, marinara, the rest of the heavy cream, and a little more kosher salt and pepper,

Place the last layer of ravioli, pour the rest of the marinara sauce over top (I added a little water to the jar, shook it, and poured over top to get all the sauce out), and the rest of the the cheese.

Cover with foil (brush olive oil on the foil side that will be touching the cheese to prevent sticking). Bake in a 375 degree oven for 40 to 45 minutes, remove the foil during the last 15 minutes.

Garnish with basil if desired.