Step 1: Heat olive oil in a large Dutch oven or a deep, large pot over medium-high heat. Add the ground beef (or beef and sausage mix) and cook, breaking it apart with a spoon, until browned. Drain any excess fat.
Step 2: Add the chopped onion to the pot and cook until softened, about 5-7 minutes. Stir in the minced garlic, dried oregano, dried basil, garlic powder, and red pepper flakes (if using) and cook for another minute until fragrant.
Step 3: Pour in the crushed tomatoes, diced tomatoes (with their liquid), beef broth (or water), salt, and black pepper. Stir well to combine. Bring the mixture to a simmer.
Step 4: Add the broken spaghetti to the simmering sauce, ensuring it's mostly submerged. Stir gently to separate the strands. Cover the pot, reduce the heat to medium-low, and let it simmer for 15-20 minutes, or until the spaghetti is al dente and most of the liquid has been absorbed. Stir occasionally to prevent sticking.
Step 5: Remove the pot from the heat. Stir in the cubed cream cheese until completely melted and smooth. Then, fold in 1 cup of shredded mozzarella cheese until it's just melted into the sauce.
Step 6: Taste and adjust seasonings if necessary. Serve hot, garnished with fresh chopped parsley or basil and extra shredded cheese, if desired. Enjoy your delicious dirty spaghetti recipe!