Preheat the oven to 170oC, gas mark 3. Lightly butter a 2 litre litre baking dish.
Spread the panettone slices with butter and then with the marmalade and cut into approx. 7cm squares. Arrange these overlapping in the dish, sprinkling with walnuts and cranberries as you go.
Beat together the milk, cream, eggs, cinnamon and sugar reserving 1 tbsp for sprinkling. Pour over the panettone and leave to soak for 15-20 minutes.
Sprinkle with reserved sugar and bake for 40-45 minutes until golden. Allow the pudding to cool slightly before serving.
Try using extra dried mixed fruit and orange zest instead of marmalade and cranberries. Great served with clotted cream.