Frosted Spice Cookies Recipe

1 c Butter, softened
1 c Sugar
1 c Molasses
1 Egg
1 c Sour milk*
6 c Flour
1 tb Baking powder
1 ts Baking soda
1 ts Ground cinnamon
1 ts Ground ginger
1/2 ts Salt
1 c Chopped walnuts
1 c Golden raisins
1 c Chopped dates