Preheat the oven to 375 degrees F.
Add sausage, egg, bread crumbs and onion into a large bowl and mix together until well combined. Use a small cookie scoop or form meatballs into about tablespoon sized balls.
Place 2 inches apart on a foiled lined baking sheet. Bake 20 minutes or until meatballs are browned and cooked through.
Meanwhile, cook ravioli according to package directions.
Add spaghetti sauce, cooked and drained ravioli and cooked meatballs together into a large pan. Cook over medium heat for about 10 to 15 minutes or until sauce is hot.
Serve with Parmesan cheese and fresh basil.