Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish and set aside.
Cook the spaghetti in a large pot of salted boiling water according to the package instructions. Drain and set aside.
In a skillet over medium heat, cook the ground beef, onion, and garlic until the meat is browned and the onion is softened. Drain any excess fat.
Add the crushed tomatoes, dried oregano, dried basil, salt, and black pepper to the skillet. Stir well and simmer for 10 minutes.
In the prepared baking dish, layer half of the cooked spaghetti, followed by half of the meat sauce, and half of the mozzarella cheese. Repeat the layers, finishing with mozzarella and Parmesan cheese on top.
Cover the baking dish with aluminum foil and bake in the preheated oven for 20 minutes. Remove the foil and bake for an additional 10-15 minutes, or until the cheese is bubbly and golden brown.
Let the casserole cool for 5 minutes before serving. Enjoy with garlic bread or a fresh salad!
Notes
This Spaghetti Casserole can be prepared in advance and refrigerated before baking. It also freezes well for up to 3 months.