Preheat the oven to 180°C (350°F). Grease a baking dish.
Combine the chopped dates and baking soda in a bowl. Pour over the boiling water and let stand for 10 minutes to soften.
In a large bowl, cream the butter and brown sugar together until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla extract.
Gently fold in the flour and the soaked date mixture until well combined.
Pour the batter into the prepared baking dish and bake for 35-40 minutes or until a skewer inserted into the center comes out clean.
While the pudding is baking, prepare the toffee sauce. In a saucepan over medium heat, combine the dark brown sugar, butter, and heavy cream. Bring to a boil, then reduce heat and simmer for about 5 minutes, stirring constantly until thickened. Stir in the vanilla extract.
Once the pudding is done, let it cool slightly. Serve warm with the toffee sauce drizzled generously over the top.