1. Preheat the oven to 350 degrees Fahrenheit (175 degrees Celsius). Grease an 8-inch square baking dish.
2. In a small bowl, combine the dates and baking soda. Pour enough boiling water over the dates to just cover them.
3. Cream 1/3 cup of butter with the white sugar. Beat in the eggs and mix well to combine.
4. Add the flour and date mixture (including the water) to the egg mixture and fold to combine. Pour the batter into the prepared baking dish.
5. Bake in the preheated oven until a tester comes out clean, 30-40 minutes. Let it cool slightly and prepare the sauce.
6. Making the caramel sauce: In a small pan, combine the brown sugar, 1/3 cup butter, and evaporated milk. Cook over a medium heat and bring to the boil. Turn the heat down and simmer for 5 minutes, stirring occasionally. Take off the heat and stir in the vanilla. Pour the sauce over individual servings of warm cake. Serve with some tasty vanilla ice cream!