Preheat oven to 180°C.
Brush the sliced panettone with the melted butter.
Place the panettone upright in an ovenproof dish and sprinkle the grated white chocolate between the slices.
Heat the milk and cream with the vanilla extract until scalding.
Whisk the eggs and the sugar together, add the cream and milk, whisk again, and strain through a sieve.
Pour evenly over the panettone. Sprinkle with muscovado sugar and bake on the middle shelf of the oven for 35 minutes.
We serve a mango, papaya, passion fruit and redcurrant salad with this pudding.