Get your ice cream out of the freezer so it can soften a little while you get things ready. Line a 2 litre pudding bowl with 3 layers of clingfilm.
Use a serrated knife to slice four 2cm thick rounds off of your panettone then cut them in half. You’ll have some panettone left over, so keep this for another time.
Arrange 6 of the slices in a single layer around the bowl and push them down if they overlap. Drizzle some Vin Santo around the sponge so it soaks in, then use the back of a spoon to smear the jam over the sponge.
Drain the cherries, and thinly slice the glacé clementines. Finely grate the clementine zest and put aside, then peel and finely slice the clementine into rounds.
Spoon one tub of ice cream into the bowl and use the spoon to spread it around in a thick layer. Sprinkle in the pistachios, cherries and glacé fruit, then layer the clementine slices on top.
Add the other tub of ice cream. Spread it out, working quickly so the ice cream doesn’t completely melt.
Put the rest of the panettone slices on top of the ice cream, drizzle over some more Vin Santo then cover the bowl tightly with clingfilm. Press a plate down on top to press everything down, then freeze overnight, or longer.
Around 20 minutes before you want to serve, unwrap your amazing winter bombe, carefully turn it out in to a serving dish, then leave to thaw slightly.
Snap up the chocolate, place it in a heatproof bowl with the butter over a pan of simmering water on low heat, and leave to melt. Leave the chocolate to melt.
Once nicely melted, stir in the reserved clementine zest, then pour the chocolate over the pudding so it oozes down the sides and looks delicious.