Preheat the oven to 180°C/160°C fan/gas mark 4.
Grease a 20cm square baking dish with butter.
Put the chopped dates into a bowl and pour the boiling water over them. Stir in the baking soda and set aside.
In a separate bowl, cream the butter and sugar together until light and fluffy. Add the eggs one at a time, beating well after each addition.
Fold in the flour and vanilla extract, then add the date mixture and stir until well combined.
Pour the batter into the prepared baking dish and bake for 35-40 minutes, or until a toothpick inserted into the centre comes out clean.
While the pudding is baking, make the toffee sauce. Melt the butter and sugar together in a saucepan over medium heat, stirring until the sugar has dissolved.
Pour in the double cream and bring the mixture to a boil, stirring continuously. Reduce the heat and simmer for 5-10 minutes, until the sauce has thickened.
Once the pudding is cooked, remove it from the oven and prick it all over with a fork.
Pour half of the toffee sauce over the pudding and let it soak in for a few minutes.
Serve the pudding warm, drizzled with the remaining toffee sauce and a dollop of whipped cream or vanilla ice cream, if desired. Enjoy!