Preheat the oven to gas 5, 190ºC, fan 170ºC. Put 12 mini muffin cases into a mini muffin tin.
Mix the flour and sugar and make a well in the centre of the mixture. Whisk together the melted butter, milk and egg, and slowly pour into the bowl, stirring gently. Add the mixed peel and currants and stir together. Divide the mixture among the 12 prepared muffin cases and bake for 20 minutes or until golden brown and risen.
Remove the muffins and place on a wire rack to cool.
To decorate, lightly dust a work surface with icing sugar and roll out 200g (7oz) of the fondant icing until fairly thin. Cut out 12 irregular rounds, about 5-7cm (2-3in) diameter, and use to top each mini muffin to resemble a white Christmas pudding topping.
Colour 50g (2oz) of the remaining fondant icing with green food colouring and the rest with red food colouring. Wash your hands afterwards. Roll out the green fondant and cut out small holly leaf shapes. Roll the red fondant into small ball shapes using your fingertips.
Finish off decorating the muffins with the leaves and berries, using just a dab of water to help them stick.