Spoon the marmalade into the bottom of a 900ml greased and floured pudding basin. Add a splash of rum or orange liqueur if using.
In a large bowl cream the butter and sugar until the mixture is pale and light and the sugar granules have dissolved completely.
Beat in the eggs one at a time and then beat in the flour. Do not over mix.
Stir in the milk. Add the orange zest. Spoon the mixture into the basin. Cover with greaseproof paper and foil, tie with string to seal and steam for 2 hours.
Let it stand for a few minutes, run a knife around the inside and invert onto the plate. Serve with custard or cream, or both!
