This can, in fact, be made with leftover Christmas pudding OR Christmas cake!
Leftover Christmas pudding or cake
A little brandy (optional)
Cut slices of the pudding or cake (no worries if it’s more of a chunk than a slice). Pour over a little brandy. Then whip the cream up into soft peaks, together with the orange zest. To bring it together, simply layer up slices of Christmas pudding / cake with generous dollops of cream, and then top with orange zest and pistachios.