Preheat oven to 350º. Line baking sheet with parchment paper (or use nonstick pans). Combine flour, soda, spices and salt. Set aside. Beat together butter, brown sugar and molasses in mixer until fluffy, 3 min. Add egg and vanilla, combining well. Add dry ingredients and mix very briefly, just until combined. Using a teaspoon, make small balls and place on sheet pan, slightly spaced apart. Bake 13-14 min, until cookies are firm and small cracks appear. Cool completely and roll in powdered sugar.