Preheat your oven to 180°C (350°F) and grease a 20cm round cake pan.
In a bowl, soak the chopped dates in boiling water for about 15 minutes.
In a mixing bowl, cream together the softened butter and brown sugar until light and fluffy.
Beat in the eggs one at a time, mixing well after each addition.
Fold in the soaked dates along with the soaking liquid and vanilla extract into the egg mixture.
Sift in the flour and baking powder, and gently fold until just combined.
Pour the batter into the prepared cake pan. Level the top with a spatula.
Bake in the preheated oven for 25-30 minutes or until a toothpick comes out clean.
While the cake is baking, prepare the toffee sauce by melting butter and brown sugar together in a saucepan.
Stir in the heavy cream and let it simmer for about 5 minutes until thickened.
Once the cake is done, pour half of the warm toffee sauce over it while it's still in the pan, allowing it to soak in.
Let the cake cool slightly before removing it from the pan. Serve warm, drizzled with the remaining toffee sauce.