Double line a 3L capacity pudding basin or bowl with plastic wrap. Set aside.
Place the chocolate ice cream into a large mixing bowl and break the Christmas pudding into it. Add half the toasted almonds.Combine well, without allowing the ice cream to melt.
Spread into the prepared basin and push the ice cream up the sides. Freeze with a smaller bowl pressed into the middle of the ice cream, to help form the hollow in the centre.
Mix the vanilla bean ice cream with the remaining nuts and cherries. Remove the extra bowl and fill the centre of the chocolate ice cream with the vanilla ice cream. Freeze overnight or at least 10 hours.
To serve, remove from the bowl. Remove plastic wrap and up turn onto the serving plate you are going to use. Drizzle the custard and /or melted chocolate over the top, being sure it runs down the sides. Return to the freezer until the toppings are solid.
Cut into wedges with a hot wet knife and serve immediately.