Line the base of a 1.5 litre/2¾ pint ovenproof dish or baking tray with a single layer of tortilla chips, then top with half of the beef mixture, then half the cheddar and half the cherry tomatoes. Add a second layer of tortilla chips, then top with the remaining beef and cheese. Transfer to the oven and cook for 8–10 mins, until the cheese has melted.