Preheat the oven to 190C/375F/Gas 5 and put 24 mini-muffin cases inside a mini-muffin tin.
Mix the flour and sugar in a bowl, then make a well in the centre. Whisk together the oil, milk and egg and slowly pour into the bowl, stirring gently. Divide this mixture between two bowls. In one bowl add the dark chocolate and mincemeat. Add the white chocolate and cranberries to the other bowl. Stir very gently.
Divide the two mixtures among the 24 muffin cases and bake for 20 minutes or until golden brown and risen.