In a medium bowl, whisk together flour, spices, baking soda, and salt; set aside. With an electric mixer, beat butter and brown sugar until smooth. Beat in molasses and egg. With mixer on low, add dry ingredients; mix just until a dough forms. Place dough on floured plastic wrap; pat into an 8-inch square. Wrap well; chill until firm, 1 to 2 hours.
bake in preheated 350 oven for 10 - 12 minutes