1. Combine the chopped Medjool dates and water in a small saucepan. Bring to a boil, then reduce heat and simmer for 5 minutes. Blend until smooth.

2. In a large bowl, cream the softened unsalted butter and dark brown sugar until light and fluffy. Add eggs one at a time, mixing well after each addition. Fold in the pureed dates.

3. In a separate bowl, whisk together the all-purpose flour and baking powder. Gradually incorporate into the wet batter until just combined.

4. Preheat oven to 350°F. Grease an 8-inch square baking dish. Pour the batter into the dish and bake for 30-35 minutes or until a toothpick comes out clean.

5. For the toffee sauce, combine heavy cream, dark brown sugar, and unsalted butter in a saucepan over medium heat. Stir until sugar dissolves and sauce thickens. Remove from heat and stir in vanilla extract.

6. Let the pudding cool for a few minutes, cut into squares, and drizzle warm toffee sauce over the top.