Preheat the oven to 200ºC and grease a square/rectangle baking dish with butter and then dust with flour. Chop the dates.
Mix the butter with the sugar. Add the golden syrup, black treacle, vanilla extract and mix again. Now add the eggs one by one and continue mixing. At low speed add the little by little the flour and baking powder. Mix until you have a smooth and thick batter
Place the chopped dates into a pan with 250 ml water. Bring to the boil and then turn the heat off. Puree the water-date mixture and then add 1 tbsp bicarbonate of soda.
Add this hot mixture to the thick batter and beat gently until mixed well and combined. Pour into the prepared baking dish and bake for 40min. the top should be firm and a skewer should come out clean.
Remove from the oven and let it cool. Once cooled take it out of the tin and cut in squares.
The sauce can be made while the pudding is baking. Melt the butter, sugar and treacle in a pan over low heat. Then add the double cream and bring the boil. Simmer for a few minutes until the sauce reaches the desired thickness. Leave to cool for a few minutes.
Prick the cooked cake all over with a skewer and then pour over the toffee sauce. Serve and enjoy.