Soak the 2 slices of bread in milk, just enough to make them moist. Mix the mince with the salt, pepper, chilli, basil, garlic and mustard in a large bowl with your hands, add the soaked bread and the egg to the mix and crush into a large ball.
Cut the mozzarella into 6 pieces and rub each piece with flour. Cover completely with the meat mixture, repeating this 12 times. Dust with the remaining flour.
Heat the oil on a medium-high heat in a large frying pan. Once the oil is hot place the meatballs into the oil and turn when each side is browned.
If using with a sauce - I recommend a homemade tomato sauce - once the meatballs are browned off, add them to your sauce for a further ten minutes before serving.
Serve with a homemade tomato sauce with pasta! Mmmmm . . . lovely.