In a small saucepan, combine the chopped Medjool dates with enough water to cover. Bring to a gentle simmer over medium heat for about 5 minutes, until the dates are soft and plump. Remove from heat, mash the dates with a fork until smooth, and set aside to cool slightly while you prepare the other ingredients.

Preheat your oven to 350°F (175°C). While it warms up, generously grease an eight-inch square baking dish with unsalted butter.

In a large mixing bowl, cream together the softened unsalted butter and dark brown sugar using an electric mixer on medium speed until the mixture is light and fluffy, about 3-5 minutes. Add the eggs one at a time, mixing well after each addition. Gradually sift in the flour and baking powder, then gently fold in the mashed dates until just combined.

Pour the batter into your prepared baking dish, spreading it evenly with a spatula. Place it in the preheated oven and bake for approximately 35 minutes or until the top is golden brown.

While the pudding is baking, prepare the toffee sauce by combining the heavy cream, dark brown sugar, unsalted butter, and vanilla extract in a medium saucepan over low heat. Stir continuously until the mixture begins to bubble and thickens slightly, approximately 8-10 minutes.

Once the Classic Sticky Toffee Pudding has cooled slightly, slice it into squares and transfer to serving plates. Drizzle the warm toffee sauce generously over each portion and serve immediately.