Preheat oven to 350°F/177°C. Grease and flour a round 8-9 1/2 inch cake pan (or 9x13-inch baking dish).
In a small bowl, stir baking soda into boiled water. Add the chopped dates and set aside.
Whip the butter and 1 cup of sugar until fluffy. Add the eggs and whip. Add dates and gently stir until well combined.
In a medium bowl, sift together the flour, baking powder, and salt. Gradually add to the date mixture and stir until combined.
Pour batter into the greased pan.
In a separate bowl, combine the chocolate chips, 1/4 cup sugar, and chopped walnuts. Sprinkle this mixture over the top of the cake batter.
Bake for 35-40 minutes, or until a toothpick inserted into the center of the cake comes out clean.