In a skillet over medium heat, cook the ground beef or sausage until browned. Drain any excess fat and transfer the meat to the crockpot.
Add the diced onion and minced garlic to the crockpot with the meat.
Pour in the crushed tomatoes, marinara sauce, and beef or vegetable broth. Stir until well combined.
Add the dried basil, oregano, salt, and black pepper into the mixture, and stir again to mix the spices evenly.
Add the uncooked pasta directly into the crockpot and stir to ensure the pasta is submerged in the sauce.
Cover the crockpot with the lid and cook on low for 4 hours, or until the pasta is cooked al dente.
About 15 minutes before serving, sprinkle the shredded mozzarella and grated Parmesan cheese on top of the pasta. Cover again and allow the cheese to melt.
Once the cheese is melted, stir gently to combine. Garnish with fresh basil or parsley if desired before serving.