Preheat the oven: Begin by preheating your oven to 350°F (175°C) and grease a 9×13 inch baking dish to ensure easy serving once it's baked.
Cook the turkey: In a large skillet over medium heat, brown 1 lb ground beef along with 1 small chopped onion and 2 minced garlic cloves. Stir constantly until the turkey is cooked through and the onions are translucent. Drain any excess fat to keep the dish light and healthy.
Add tomatoes and simmer: Stir in 1 jar (24 oz) marinara sauce and 1 can (15 oz) crushed tomatoes. Allow the mixture to simmer for about 5 minutes to combine the flavors.
Prepare the creamy filling: In a separate bowl, combine 1 cup ricotta cheese, 1/2 cup sour cream, and 1 package (8 oz) softened cream cheese. Mix until smooth and well blended.
Layer the casserole: Begin layering by spreading half of the meat sauce in the greased baking dish. Top it with half of the 1 package (25 oz) frozen cheese ravioli, followed by the creamy cheese mixture and 1 cup shredded mozzarella cheese.
Repeat the layers: Add another layer of the meat sauce, followed by the remaining ravioli. Finish by spreading the rest of the meat sauce on top and sprinkling with the remaining 1 cup shredded mozzarella cheese and 1/2 cup grated Parmesan cheese.
Season: Sprinkle 1 tbsp Italian seasoning, salt, and pepper over the top layer to enhance the flavors.
Bake: Cover the baking dish with aluminum foil and bake for 30 minutes. Then, uncover and bake for an additional 15 minutes, or until the cheese is bubbly and golden brown.
Garnish and serve: Once baked, let the casserole cool slightly. Garnish with fresh chopped parsley if desired, and it's ready to enjoy!