Preheat your oven to gas mark 3 (or 160C for electric ovens).
Cut the panettone into rough slices (crusts and all) and butter them on each side.
Arrange them in a large oven dish sandwiching segments of Terry's chocolate orange in between each layer.
In a separate bowl whisk together the eggs, cream, milk, vanilla and advocat.
Pour evenly over the panettone slices.
Just before putting into the oven, sprinkle with light brown sugar.
Put the dish into the centre of your oven and bake for 40-45mins until the pudding is set but still with a little bit of a wobble and the top is crisp and golden.
Serve with single cream (or if you are feeling particularly luxurious, brandy butter!)