Rolling the dough in turbinado sugar gives the cookies a sugary edge. Turbinado sugar is a coarse, blond-colored sugar with a delicate molasses flavor; look for it in your grocery's baking section.
Combine first 4 ingredients in a bowl; set aside. Beat margarine at medium speed of a mixer until light and fluffy. Gradually add granulated sugar, beating at medium speed of a mixer until well-blended. Add vanilla and egg white, and beat well. Add flour mixture, and stir until well-blended. Turn dough out onto wax paper; shape into a 6-inch log. Wrap log in wax paper; freeze 3 hours or until very firm.
Preheat oven to 350°.
Roll log in turbinado sugar. Cut log into 24 (1/4-inch) slices; place 1 inch apart on a baking sheet coated with cooking spray. Bake at 350° for 8 to 10 minutes. Remove from pan; cool on wire racks.
Chocolate-Peppermint Variation: Substitute 1 teaspoon of peppermint extract for the vanilla extract.