In a large bowl, sift together flour, baking soda and baking powder; set aside. With an electric mixer fitted with paddle attachment, cream butter and sugar until fluffy. Mix in spices and salt, then egg and molasses. Add flour mixture; combine on low speed. Wrap dough in plastic; chill for at least 1 hour. Heat oven to 350ºF/180ºC. On a floured work surface, roll dough 1/8 inch/3 mm thick. Cut into desired shapes. Transfer to ungreased baking sheets. Bake until crisp but not darkened, about 8 to 10 minutes. Let cookies cool on wire rack, then decorate as desired. Makes about 3 dozen.
Combine all ingredients; beat until smooth.
Decorate with icing, Watkins Artificial Dye-Free Decorating Sugars and Sprinkles