Preheat oven to 180°C/Gas 4. Oil a 25cm x 18cm/10in X 7in non-stick baking tin that is at least 2.5cm/1in deep. Line with parchment paper.
Place the dates in a pan with 300ml/1/2 pint of water and bring to the boil, then simmer for 5 minutes until softened. Remove from the heat and stir in the bicarbonate of soda until the mixture stops foaming.
Place 50g (2oz) of the butter and the caster sugar in a large bowl and cream together until well combined, then beat in the vanilla essence. Gradually add the eggs, beating well after each addition. Fold in the flour with a metal spoon and finally fold in the date mixture. Pour into the greased baking tin and cook for about 35-40 minutes until well risen and firm to the touch.
To make the toffee sauce, simply place the remaining 115g (4oz) of butter, the dark muscovado sugar and honey or golden syrup in a pan and gently heat, stirring until the sugar has dissolved. Bring to a simmer and cook for 2-3 minutes until combined, then remove from the heat.
When the pudding is cooked, remove from the oven and after 5 minutes turn out on to a wire rack to cool completely.
To serve, cut the pudding into portions and arrange on plates. Pour over some of the toffee sauce. Serve the remainder of the sauce separately.
