Cook the spaghetti according to package instructions until al dente. Drain and set aside.
In a large skillet over medium heat, add the ground beef and cook until browned. Drain excess fat.
Add the chopped onion and minced garlic to the beef. Cook until the onion is translucent.
Stir in the crushed tomatoes, tomato paste, bell peppers, oregano, basil, cayenne (if using), salt, and pepper. Let simmer for about 10 minutes, allowing the flavors to meld.
In a large bowl, combine the cooked spaghetti with the beef mixture and cream cheese until evenly mixed.
Transfer the spaghetti mixture to a greased 9x13 inch baking dish.
Sprinkle shredded mozzarella and cheddar cheese evenly over the top.
Cover with aluminum foil and bake in the preheated oven for 25 minutes.
Remove the foil and bake for an additional 10 minutes, or until the cheese is bubbly and golden.
Once done, let it cool for about 5 minutes. Garnish with fresh parsley before serving.
Notes
Serve straight from the dish, or for an elevated presentation, scoop individual servings onto plates and garnish with additional parsley for a pop of color.