In a skillet over medium heat, cook ground beef and diced onion until beef is browned and onion is softened. Drain excess fat.
Stir in taco seasoning and diced tomatoes. Cook for 2–3 minutes until heated through.
Prepare spaghetti according to package instructions. Drain and add to the skillet with beef mixture.
Sprinkle cheddar and mozzarella cheese over the top and stir until melted and evenly combined.
Enjoy warm!
Preparation Time: 10 minutes
Cooking Time: 20 minutes
Servings: 4
Calories: Approx. 500 per serving
