Cook the French fries following pack instructions. Meanwhile, heat the olive oil in a frying pan and fry the onion for 10 mins. Add the garlic and chilli flakes, and fry for 5 mins more. Tip in the tomatoes, oregano and sugar, then simmer for 10 mins.

In another pan, fry the beef meatballs for 5 mins until browned, then add to the sauce and bubble for 5 mins, or until cooked through. Put the fries in a heatproof dish and top with the meatballs and sauce. Scatter over the mozzarella and cheddar. Grill for 2-3 mins until the cheese has melted. Season and serve.