Preheat your oven to 375°F (190°C).

Bring a large pot of salted water to a boil, then cook the ravioli according to package instructions until al dente. Drain and set aside.

In a large skillet over medium heat, cook the Italian sausage, breaking it into crumbles, until browned and cooked through. Drain excess fat.

Add the minced garlic to the sausage and cook for 1 minute until fragrant. Remove from heat.

In a medium bowl, combine the marinara sauce, heavy cream, Italian seasoning, and crushed red pepper flakes. Stir well to blend.

In a large mixing bowl, gently toss the cooked ravioli, sausage mixture, chopped spinach, and sauce until evenly coated.

Transfer half of the ravioli mixture to a greased 9x13 inch baking dish. Sprinkle with 1 cup mozzarella cheese and 1/4 cup Parmesan cheese.

Add the remaining ravioli mixture on top and finish with the remaining mozzarella and Parmesan cheese.

Cover the casserole with foil and bake for 25 minutes. Remove the foil and bake for an additional 10-15 minutes or until the cheese is bubbly and golden.

Let the casserole rest for 5 minutes before serving, then garnish with fresh chopped basil.