Cream the sugar and shortening together, then add the eggs and blend well. Add the peach puree and the dry ingredients. Mix well. Add the vanilla and chopped nut, if used, stirring until well blended. Spoon into muffin tins that have been sprayed with a non-stick coating. Bake at 325 degrees F. for 25 to 30 minutes or until done. Let cool in the tins for a few minutes before removing them to a rack to cool.