The richness of panettone makes it an excellent substitute for plain white bread, and it even comes with it's own complement of dried fruit in it so no need to add them either. The recipe below is slightly cobbled together from what I happened to have in the fridge, but the proportions of cream and milk can be increased if you want.
Recipe (enough for 6)
Around 500g panettone, sliced
250ml double cream
250ml milk (ideally whole but I used semi-skimmed)
3 cardamom pods, lightly crushed to release the seeds
1 bay leaf
Around 50g butter
Around 3 tblsp caster sugar
1 egg yolk
Gently heat the milk and cream with the cardamom, bay leaf and initially 2 tablespoons of the sugar. Have a taste and then add more sugar as required. Leave this mix on a low heat for around 15-20mins, until it's reduced by around a quarter and thickened a little. Take it off the heat and leave to cool for a while. In the meantime beat the egg yolk thoroughly, and once the cream mix is just warm rather than hot, pour a little onto the egg. Continue to whisk well and pour on the rest of the cream. Scoop out the cardamom pods and bay leaf, and set to one side.
Melt about half of the butter in a frying pan, and when it's lightly foaming put in the panettone slices and cooked until slightly browned on both sides. Add more butter as it's needed. As the panettone is quite rich already this step might not be necessary but thought I'd stick to family tradition.
To assemble the pudding, find a dish that will hold two layers of panettone. Place slices on the bottom, overlap them a bit, and repeat for another layer on top. Pour the cream mixture over the top and push the panettone into it so that gets to soak up some of the liquid. The panettone shouldn't be floating in cream but you should be able to see some when you push the pudding down a bit. Dot a few bits of butter over the top and bake in the middle of the oven at gas mark 5 for around 25mins. The top of the pudding should be golden so cover with foil if it looks like it's scorching.
NB Some Twitter discussion revealed that this pudding might well have been influenced by another desert from the Indian sub-continent, shahi turka, which very unusually for me I had never heard of before. Anyway, here's to fusion cooking in all its forms!