Step 1

Preheat oven to 350°F (180°C). Spray a large baking dish with cooking spray and set aside. A deep 11 x 7-inch dish works well, but you can also use a 9 x 13-inch dish.

Step 2

Heat about 2 teaspoons of olive oil in a large skillet over medium-high heat. Sautee onion until just tender (about 3-5 minutes). Add ground beef and cook until no longer pink. Drain fat from the skillet. Season with salt and pepper, to taste, and stir in marinara sauce.

Step 3

Meanwhile, cook spaghetti according to package instructions. Drain.

Step 4

Add cooked pasta to the meat sauce and stir to combine.

Step 5

Pour into prepared baking dish. Sprinkle with grated cheese.

Step 6

Bake, uncovered, for about 25-30 minutes.