01 -
In a large (10-12") cast iron skillet, sauté diced onions in olive oil over medium-low heat. Add crushed garlic and continue sautéing until onions are tender.
02 -
Add cooked meatballs, marinara sauce, and Italian seasoning to the skillet. Heat over medium-low for about 20 minutes.
03 -
In a separate large pot, cook spaghetti noodles according to the package instructions, undercooking by 2 minutes.
04 -
Using a large slotted spoon, remove the meatballs from the sauce and set aside. Scoop cooked spaghetti directly into the marinara sauce. Add 1/2 cup pasta cooking water and gently stir to coat the pasta fully in sauce.
05 -
Place the meatballs back on top of the pasta. Sprinkle grated cheese and parmesan cheese over the dish. Bake at 350°F (175°C) for 20-30 minutes, or until hot, bubbly, and the cheese is melted.