Place half of the tortilla chips into a bowl and spread half of the salsa on top. Cut some spring onions and sprinkle a few over the tortilla chips and salsa. You will then need to repeat the above again, so basicly you are adding another layer of tortilla chips, salsa and spring onions! Make up the cheese sauce mix and pour over the top of the dish. Sprinkle grated cheese and the remaining spring onions and pop in the oven until the cheese has melted.