Lightly grease four individual pudding basins with a little TREX, then add 1 tbsp. chocolate spread to each basin.
Sift the flour, cocoa powder and salt into a mixing bowl. Add the sugar, TREX, unbeaten egg, milk and vanilla extract. Use a wooden spoon to beat the mixture together until smooth and creamy – this will only take 1-2 minutes.
Share the mixture equally between the pudding basins and level the tops. Cover each one tightly with a piece of foil.
Place the basins in a steamer, cover with the lid and steam steadily for 30-35 minutes, taking care that the steamer does not boil dry – top up with boiling water if necessary.
Carefully turn out the puddings and serve with custard.