Stir flour, spices, baking soda, and salt together in a bowl, set aside. Cream butter, and brown sugar together until smooth. Beat in egg, vanilla, then gradually stir in flour mixture.
Fold in butterscotch chips, chill dough until firm, about an hour.
Preheat oven to 350 degrees, lightly grease cookie sheets, or use parchment paper to line sheets. Roll dough into balls, arrange on cookie sheets, spacing three inches apart. Bake 12-14 minutes, until golden. Let cookies cool on cookie sheet for a few minutes, then transfer to rack.
Recipe by I'm At Home Baking! at http://imathomebaking.com/25-days-of-christmas-cookies-day-15-butterscotch-spice-cookies/