Chop the pitted dates into small pieces and place them in a heatproof bowl. Pour over boiling water, add baking soda, and stir. Let soak for 10 minutes until the dates are soft and jammy, then drain, reserving a couple of tablespoons of the soaking liquid.
In a large mixing bowl, cream together softened butter and dark brown sugar until the mixture is smooth and slightly fluffy, about 2-3 minutes. Use a spatula or hand mixer for best results.
Add eggs one at a time to the butter mixture, beating well after each addition. Mix in vanilla extract until fully incorporated and the mixture is light and silky.
Stir the soaked dates into the batter, then gently fold in the self-raising flour until just combined. If the batter feels thick, add a little of the reserved soaking liquid to loosen it slightly.
Pour the batter into a greased baking dish or individual ramekins, smoothing the top with a spatula. Bake in a preheated oven at 180°C (350°F) for 25-30 minutes, until the top is golden and a toothpick inserted in the center comes out moist but not wet.
While the pudding bakes, make the toffee sauce by combining brown sugar, butter, and heavy cream in a saucepan. Bring to a gentle boil over medium heat, stirring constantly, until the sauce thickens slightly and becomes glossy, about 3-4 minutes. Remove from heat and stir in vanilla extract.
Once the pudding is baked and still warm, poke holes all over the surface with a skewer or fork. Pour the hot toffee sauce evenly over the pudding, allowing it to soak in and create a sticky, caramelized coating.
Let the pudding rest for about 5 minutes to allow the sauce to set and the flavors to meld.
Serve slices of the warm sticky toffee pudding drizzled with extra toffee sauce, optionally with cream or ice cream on the side. Enjoy the gooey, caramel-rich texture and warm aroma with each bite.
