Cook the Spaghetti:
Cook the spaghetti according to the package directions until al dente. Drain and set aside.

Prepare the Meat Sauce:
In a large skillet, cook the ground beef or sausage over medium heat until browned and fully cooked. Drain any excess fat. Add the marinara sauce, garlic powder, onion powder, dried oregano, salt, and pepper. Stir to combine and simmer for 5-10 minutes. Remove from heat.

Mix the Creamy Cheese Filling:
In a separate bowl, combine the softened cream cheese, sour cream, and ricotta cheese. Mix until smooth and well combined.

Assemble the Casserole:
Preheat the oven to 350°F (175°C). In a greased 9×13-inch baking dish, spread a layer of the meat sauce on the bottom. Then add half of the cooked spaghetti on top of the sauce. Spread half of the creamy cheese mixture over the spaghetti. Repeat the layers with the remaining meat sauce, spaghetti, and cheese mixture.

Add Mozzarella and Parmesan:
Top the casserole with shredded mozzarella cheese and grated Parmesan cheese.

Bake:
Cover the casserole with aluminum foil and bake in the preheated oven for 25 minutes. Remove the foil and bake for an additional 10-15 minutes, or until the cheese is melted and bubbly.

Serve:
Once baked, remove from the oven and let it sit for a few minutes before serving. Garnish with fresh parsley if desired.