Preheat the oven to 190°C /Gas 5. Whisk together the cream, milk and eggs. Slice the vanilla pod/bean in half and scrape the seeds into the egg and cream mixture. Add the caster/superfine sugar and whisk some more.
Slice the panettone into thick slices and butter each slice. Arrange the buttered panettone slices in an ovenproof dish. Scatter with the apple and sprinkle with a pinch of nutmeg.
Pour over the cream mixture and make sure the panettone is evenly soaked. Sprinkle the top with brown sugar.
Place in the oven for 20 to 30 minutes or until golden and crispy.