Combine the meat, egg, parmesan, garlic and parsley in a medium bowl and mix well to combine. Add salt, nutmeg and breadcrumbs. Mix thoroughly. Shape tablespoonfuls into firm meatballs and place into a tray with flour.
Heat the oil in a large frying pan. Fry the meatballs in batches for 3 minutes, until browned all over and cooked. Put in plate with kitchen paper. Set aside
Heat the oil in a medium saucepan over medium heat and cook the onion until softened. Add the tomato and bring to the boil. Decrease the heat to low and gently simmer for 15 minutes, until flavors have developed. Season with salt and pepper, and basil leaves. Add the meatballs and cook for a further 5 minutes.
Serve hot, share and enjoy!