Put the butter, syrup and sugar in a saucepan and heat gently, stirring until the butter has melted. Mix the flour, baking powder and ground ginger in a bowl. Beat the eggs and milk in another bowl.
Remove the butter saucepan from the heat, then beat in the flour mixture. Gradually beat in the egg and milk mixture, then stir in the chopped glacé ginger.
Divide the mixture evenly among paper cake cases arranged in a 12-hole deep muffin tin and bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 10–15 minutes until well risen and cracked. Leave to cool in the tin.
Make the icing. Sift the icing sugar into a bowl and gradually mix in the water to create a smooth spoonable icing. Drizzle random lines of icing from a spoon over the muffins and complete with slices of glacé ginger. Leave the icing to harden for 30 minutes before serving.