Step 1

Preheat oven to 350° F.

Step 2

Bring a large pot of salted water to a boil. Break the spaghetti noodles in half and add them to the boiling water. Cook according to the package directions for al dente. Drain and set aside.

Step 3

Meanwhile, heat the olive oil in a large skillet over medium heat. Add the onion and cook, stirring often, for 2 minutes.

Step 4

Add the ground beef to the skillet and increase the heat to medium-high. Cook, crumbling the meat, until browned. Drain off excess grease.

Step 5

Add the garlic to the pan and cook, stirring, for 30 seconds. Then stir in the marinara sauce, Italian seasoning, salt and pepper.

Step 6

Reduce the heat and cook the sauce at a low simmer for 5-10 minutes, stirring occasionally.

Step 7

Stir in ¼ cup of the grated Parmesan. Then stir in the cooked spaghetti, mixing it well with the sauce.

Step 8

Transfer the spaghetti and sauce mixture to a 13x9-inch baking dish. Sprinkle the mozzarella cheese evenly over the top, followed by the remaining ¼ cup Parmesan.

Step 9

Cover the dish with foil (spray the underside lightly with cooking spray to keep the cheese from sticking to the foil).

Step 10

Bake for 30 minutes. Then uncover and bake for 10-15 minutes more, until the casserole is hot and the cheese is golden brown. Serve, garnished with chopped fresh parsley or basil, if desired.