Butter one side of each slice of bread. Arrange the slices in a lightly greased ovenproof dish, with the buttered sides down, sprinkling the sultanas and cranberries between the layers.
Beat eggs with the sugar and stir in milk, coconut milk, water and salt. Pour over the bread and let stand for five to 10 minutes.
Sprinkle with cashew nuts and nutmeg. Stand the dish in a roasting pan. Pour in hot water to come halfway up the sides of the dish. Bake in a preheated oven at 180°C or until a knife inserted in the centre comes out clean. Serve warm. The pudding can also be served chilled.