Preheat the oven to 200°C/180°C fan/400°F. Grease 6 pudding moulds with a little butter.
In a bowl, beat together the butter and demerara sugar until combined and light gold, then add the golden syrup and mix again.
Crack the eggs into a small bowl and add the treacle. Beat them together and pour a splash of the mixture into the butter and sugar. Beat to combine and scrape the sides of the bowl clean with a spatula. Add a tablespoon of the pre-weighed flour and again beat to combine. Repeat with the egg and treacle, and then a spoonful of flour, continuously scraping the bowl. Continue until all the egg and treacle is incorporated.
Grate in the orange zest and add the juice, as well as the small chunks of stem ginger and mix them into the batter.
Add the rest of the flour and ground ginger and stir to combine – you can be as vigorous as you want, you don’t need to carefully fold.
Pour the dates or prunes into the food processor along with the boiling water. Blitz until smooth then add the vanilla and bicarb. The purée will immediately froth like homemade honeycomb so quickly pour the mixture into the cake batter and fold together.
Pour the pudding mixture into the moulds – they will be quite full. Stand them on a baking tray and slide it into the oven to bake for 20-25 minutes, until they are well-risen and springy, and a skewer is inserted into the centres and comes away with a few sticky crumbs – you don’t want it to be completely clean as the puddings need to be lovely and moist!
Meanwhile make the caramel sauce. Put everything in a saucepan and set it over medium heat. Bring to the boil and simmer for 5 minutes until deep gold and slightly thickened.
Remove the sponges by running a cutlery knife around the edge; they should plop out easily. Serve drizzled in sauce, with vanilla ice cream on the side.