1.To make Yogurt Guacamole, combine avocado, lime juice, yogurt, coriander, spring onions and season to taste. 2. Arrange 1/2 the grated cheddar cheese over four tortillas, top with apple slices and remaining grated cheese. Place remaining tortillas on top and brush with melted butter. 3. Cook for 1 minute in a hot non stick frypan until lightly browned. Turn over and cook for a further minute. 4. Cut into wedges and serve with Yogurt Guacamole.