Puree persimmons until smooth and stir in baking soda. Mix well. It will set. Weird but not to worry.
Beat butter and sugar until fluffy. Add egg and persimmon mixture. Combine flour and spices and add to persimmon mixture. Blend well, stir in nuts and zest. Spoon into a 9 inch greased cake pan. Bake at 350 for about 40 or more until knife comes out clean.
Before serving, sprinkle with powdered sugar This recipe can be increased with no adverse effects, except perhaps your waistline. The cake freezes well, although don't powder sugar until it's time to serve.
The original recipe calls for 2 tsp of baking powder, to be added with the flour. However, it was rather serendipitous that our baker over looked it. The resulting cake is very moist and dense but not too heavy. You can try with the baking powder if you want. But our version omits it.