Sift together flour, baking powder, soda, salt and nutmeg. Set aside. Beat butter, sugar and egg on medium until light and fluffy. Add sour cream and vanilla(flavoring) extract. Beat on low speed. Gradually add all flour mixture. Wrap dough in wax paper and refrigerate several hours or overnight.
Preheat oven to 375º.
Roll out dough thin to make cut out cookies(Christmas, Easter, any holiday,Birthday)
Bake 10-12 minutes
Cool on wire racks or paper. Frost with Royal Frosting.
Mix all ingredients on low speed until thoroughly mixed. Divide and add food coloring to make colors for frosting cookies. Decorate(any other decoration, sprinkles, colored sugars,etc)
Let set to dry several hours or over night.