Prepare the Meatballs: In a large bowl, combine ground beef, ground pork (or tofu), breadcrumbs, Parmesan cheese, parsley, minced garlic, egg, oregano, basil, and red pepper flakes. Season with salt and pepper. Mix until just combined—do not overmix.
Shape the Meatballs: With your hands, shape the mixture into 1.5-inch meatballs and place them on a baking sheet.
Brown the Meatballs: In a large skillet, heat olive oil over medium heat. Add the meatballs in batches, browning them on all sides (about 5-7 minutes). Remove and set aside.
Make the Sauce: In the same skillet, add the crushed tomatoes and bring to a simmer. Add salt and additional herbs if desired.
Combine: Gently add the browned meatballs back into the skillet with the sauce. Cover and let them simmer in the sauce for about 20 minutes, allowing flavors to meld.
Cook the Spaghetti: While the meatballs are simmering, cook the spaghetti according to the package instructions. Drain and set aside.
Serve: Plate the spaghetti and top with the meatballs and sauce. Sprinkle extra Parmesan and parsley if desired.
Notes
For a vegetarian option, substitute ground pork with tofu.