Whisk together the eggs, milk and cinnamon in a mixing bowl. Pour into a shallow dish, then dip each piece of bread in the mixture, making sure to soak both sides.
Heat half the butter in a large frying pan over a medium heat, then fry the bread in batches until golden brown on both sides. Remove from the pan and place on a plate, covering with foil to keep warm.
Heat the remaining butter in the pan and saute the apples for 3-4 minutes, tossing occasionally. Arrange the toast on serving plates and top each slice with 3 slices of apples. Dust generously with the icing sugar. Serve immediately.