Preheat oven to 350°F and spray a 13x9 baking dish with nonstick spray.
Cook the spaghetti, per package directions, to al dente and drain.
16 ounces dry spaghetti
While the spaghetti cooks, brown the beef in a large skillet set over medium heat. Break the beef up with a wooden spoon as it cooks.
1 pound ground chuck
Drain the beef and wipe out the skillet.
In the same skillet, add the oil and butter. Add onions and cook until onion has softened and is translucent, about 4-5 minutes. Add minced garlic and cook an additional 30 seconds.
1 tablespoon olive oil, 1 tablespoon unsalted butter, 1 medium yellow onion, 3 garlic cloves
Add the beef, marinara sauce, 1 tablespoon chopped basil, and ¼ cup grated parmesan cheese. Stir until well combined and season with kosher salt and freshly ground black pepper.
24 ounces marinara sauce, 2 tablespoons chopped fresh basil, ½ cup grated parmesan cheese, Kosher salt and freshly ground black pepper
Add the cooked spaghetti to the skillet with the meat sauce mixture and stir until spaghetti is well coated.
Transfer the spaghetti mixture to the prepared baking dish and sprinkle with mozzarella and remaining ¼ cup parmesan cheese.
1 cup shredded mozzarella
Bake at 350°F for 20-30 minutes or until cheese has melted and the spaghetti is hot throughout.
Garnish with the remaining chopped basil and serve.