To Make Pudding:
Preheat oven to 350 F. Butter a 10-inch round or square baking dish and set aside. In a bowl, sift the flour and baking powder and set aside. In a small bowl combine chopped dates, boiling water and baking soda and set aside. In a mixing bowl using a stand or hand mixer, cream the butter and sugar until light and fluffy. Add the egg and vanilla to butter mixture and beat until blended. Add in 1/3 of the flour mixture and beat until combined. Continue to add remaining flour 1/3 at a time until completely combined. Using a spatula, fold in the date mixture to the batter and fold until blended.
Pour batter into the prepared baking dish. Bake until pudding is set and firm on top, about 35 minutes. Remove from oven to a wire rack.
To Make Toffee Sauce:
In a small, heavy-bottomed sauce pan, combine the butter, heavy cream and brown sugar. Heat the mixture to boiling over medium low fire while stirring constantly. Boil gently until mixture is thickened, about 8 minutes. Spoon about 1/3 cup of the sauce over the pudding. Spread evenly on top. Place pudding under the broiler until the topping is bubbly, about 1 minute. Serve immediately. Drizzle with remaining toffee sauce and top with a spoonful of whipped cream.