18 1-inchfully cooked Italian meatballshomemade or store-bought
1 1/2cupsmozzarella cheeseshredded
Start water boiling for pasta and preheat oven to 375F.
In a large ovenproof skillet, heat olive oil over medium heat. Add onion and cook, stirring, until softened. Add garlic and red pepper flakes, if using, and cook, stirring, another minute. Add marinara sauce. Bring to a boil, then reduce heat to low and allow to simmer while pasta cooks.
Break spaghetti in half and add to boiling water. Boil for about 1-2 minutes less than the package suggest. Drain pasta , then add pasta to the warm marinara sauce in skillet. Toss to combine, then level top. Press cooked meatballs into the spaghetti, leaving about 1/3-1/4 exposed on top. Cover skillet with aluminum foil and place into preheated oven. Cook for 15 minutes. Remove from oven. Remove aluminum foil. Sprinkle shredded cheese overtop, then return to the oven uncovered and bake for an additional 10 minutes, or until cheese is melted and golden in spots.
Be sure to read the "Cook's Notes" in the original post, for more tips, options, substitutions and variations for this recipe!