1. Bring a large pot of salted water to a boil. Add the spaghetti and cook until al dente according to the package directions. Drain and set aside, reserving about 1/2 cup of pasta water.

2. In a large skillet over medium-high heat, add the ground beef. Break it apart and cook until browned, about 6–8 minutes. Drain excess fat if needed.

3. Add the chopped onion to the skillet and cook until soft and translucent, about 4–5 minutes. Stir in the minced garlic and cook for 30 seconds.

4. Pour in the marinara sauce. Add Italian seasoning, salt, and black pepper. Stir to combine and reduce heat to low. Let it simmer for 10–15 minutes.

5. Add the cubed Velveeta cheese to the sauce. Stir until fully melted and the sauce is creamy. Add a splash of reserved pasta water if needed to loosen the sauce.

6. Add the cooked spaghetti to the skillet and toss to coat the noodles evenly in the creamy beef marinara sauce.

7. (Optional) Transfer the pasta to a baking dish, top with mozzarella, and broil for 2–3 minutes until bubbly and golden.

8. Garnish with chopped parsley if desired and serve immediately.