Preheat your oven to 350°F (175°C). Grease and flour an 8-inch round cake pan.
In a bowl, combine chopped dates and hot water. Stir in baking soda and let sit for 10 minutes to soften.
In a large mixing bowl, cream together butter and brown sugar until light and fluffy.
Beat in the eggs one at a time, followed by vanilla extract.
In another bowl, whisk together flour, baking powder, cinnamon, and nutmeg.
Gradually add the dry ingredients to the wet mixture, alternating with the soaked dates (including the liquid), until well combined.
Fold in chopped walnuts if using.
Pour the batter into the prepared cake pan and smooth the top.
Bake for 35-40 minutes or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for 10 minutes before transferring to a wire rack to cool completely.