Mix 3 tbsp of the butter with half the cinnamon and mash together. Beat together the egg, milk and remaining cinnamon. Sandwich 2 slices of hot cross bun together with half the cinnamon butter and repeat with the remaining two slices.
Dip in the egg mix and leave to soak for a few secs. Heat the butter in a frying pan until foaming. Cook the hot cross buns for 1-2 mins each side until light golden (you may need to do this in two batches). Press down on them as you cook. Serve each portion topped with a scoop of ice cream and a drizzle of maple syrup, if you like.