Preheat the oven to 375F.
Line a baking tray with non-stick paper.
In a bowl, mix together the ground pork and beef, onion, garlic, salt, pepper, basil, parsley, bread crumbs and milk.
Shape into 8 to 10 balls about two inches in diameter. Arrange on the prepared baking tray and cook in the oven for 20 minutes.
Take the meatballs out of the oven and arrange on a heatproof plate that you will serve them in.
Spoon a heaping tablespoonful of tomato sauce over each meatball. Top with a slice of cheese.
Put back in the oven and cook for another 10 minutes or until the cheese is melted and the sauce is bubbly.
Sprinkle with more chopped parsley or basil, or both, before serving.