Preheat your oven to 180°C (350°F). Grease and line a 9-inch loaf pan or round cake tin with parchment paper.
Place the chopped dates in a bowl. Pour the boiling water over them and stir in the baking soda. Let the mixture sit for about 10 minutes so the dates soften.
In a large bowl, beat the butter and brown sugar together until light and creamy.
Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
In another bowl, whisk together the flour, baking powder, and salt.
Gradually fold the dry ingredients into the butter mixture.
Stir in the softened date mixture along with the chopped walnuts. Mix gently until everything is combined.
Pour the batter into the prepared cake pan and smooth the top.
Bake for 35–45 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cake to cool in the pan for about 10 minutes, then transfer it to a wire rack to cool completely.
