Place the tomato paste, stewed tomatoes, garlic, parsley, pepper, salt and oregano in a food processor. Blend everything until you have achieved a smooth mixture.
Place a large skillet over medium heat. Add olive oil and let it heat . Saute onion for 2 minutes then add in white wine and the tomato sauce mixture. Simmer for 30 minutes, stirring occasionally.
Mix the pork, veal, and beef in a big bowl. Add the cheese, eggs, salt, pepper, parsley and garlic to the mix. Add in the breadcrumbs then water, ½ cup at a time. It will take you about ½ to 1 cup to moisten the mixture properly. Using your hands, shape the mixture into balls.
Place skillet over medium heat and fry the balls for a few minutes on each side.
Cook the pasta following the instructions that are written on the label.
Place marinara sauce in a skillet over medium-high heat. Add in the meatballs and fully coat the balls with sauce. Simmer for 5 minutes. Add the pasta to the skillet and mix everything well.
Transfer the pasta mixture to a casserole dish. Arrange the meatballs on top. Top off with mozzarella cheese. Bake the dish at 350 degrees for 30 minutes. The cheese should be melted and bubbly by then.
Garnish with chopped fresh basil leaves.