Preheat the oven to 180 C degrees. Grease and line the base of a 7cm deep, 22cm (base) cake pan. You can also do individual cakes in greased pudding moulds.
Place dates and bi carbonate of soda into a bowl. Pour over boiling water. Allow to stand for 10 - 20 minutes. Mash with a potato masher or fork until it resembles sloppy porridge.
Using an electric mixer, beat butter, sugar and vanilla until pale and creamy. Add eggs, 1 at a time, beating well after each one. Using a large metal spoon, fold through date mixture and flour until well combined.
Spoon mixture into prepared cake pan. Bake for 35 to 40 mins or until a skewer inserted into the centre comes out clean. Turn onto a plate.
Make sauce. Combine all sauce ingredients in a saucepan over medium heat. Cook, stirring often, until sauce comes to the boil. Reduce heat to medium-low. Simmer for 2 minutes.
Pierce pudding all over with a skewer. pour 1/2 cup of the butterscotch sauce over the warm pudding. Serve warm with remaining sauce and a big dollop of ice-cream.