Preheat your oven to 350°F (175°C). In a large mixing bowl, combine the egg, chopped parsley, tomato paste, oregano, salt, pepper, minced garlic, and a splash of water. Add in the ground beef, ground pork, bread crumbs, and Parmesan cheese. Mix gently but thoroughly and form into meatballs. Bake for 20 minutes.

In a skillet, melt butter over medium heat. Sauté chopped onion for 5 minutes, then add minced garlic and cook for 1 minute. Stir in marinara sauce and simmer for 5-7 minutes before adding heavy cream.

Add cooked spaghetti to the creamy sauce, stirring for 5 minutes. Fold in baked meatballs, serve topped with extra Parmesan.