Grease a 12-section muffin tray, preferably nonstick. Put the treacle and butter in a small saucepan and heat gently until the butter has melted. Whisk together the egg and milk with a fork in a jug and stir in the treacle and butter.
Put the flours, baking powder, salt and caraway seeds in a bowl and add the wet ingredients. Stir gently until the ingredients are evenly combined. Divide the mixture between the tin sections.
Bake in a preheated oven, 220°C (425°F), Gas Mark 7, for 15 minutes or until well risen. Transfer to a wire rack. Serve warm or cold.