Place the minced beef, sausage meat, chopped onion, egg, parmesan, breadcrumbs, Worcestershire sauce and a good pinch of salt and pepper into a large bowl. Mix everything together using your hands, then form the mixture into walnut-sized meatballs - you should get 40-45 meatballs.
Place the meatballs into two or three large baking dishes - try to make sure they're not touching. Brush the olive oil over the meatballs and place in the oven for 10 minutes.
Take the meatballs out of the oven and push them over to one side of the baking dishes. Divide the garlic, tinned tomatoes, tomato puree, thyme, oregano and brown sugar between the dishes (doesn't have to be exactly equal) and give the mixture a stir. Now move the meatballs back over, so they're evenly distributed in the sauce.
Top with the mozzarella and cheddar and place back in the oven for 15-20 minutes until the sauce is bubbling and the cheese is golden brown (it's a good idea to put your pasta on at this time too).
Take out of the oven and serve, sprinkled with freshly chopped parsley.
You can easily halve or even quarter this recipe if you don't want to make such a large portion.If you want to make this recipe ahead and freeze it, cook the meatballs up to the end of step 3, then remove from the oven and leave to cool. Pour over the sauce ingredients and cheese, then cover and freeze. Defrost thoroughly, then cook for 20-25 minutes, uncovered at 190c/375f..Nutritional Information is per serving.