Lightly spoon flour into a dry measuring cup; level with a knife. Combine flour and next 4 ingredients in a medium bowl; whisk to blend.
Place sugar and butter in a large bowl; beat with a mixer at medium speed until well blended. Add egg and lemon rind, beating well. Add flour mixture and buttermilk alternately to sugar mixture, beginning and ending with flour mixture. Spoon batter into an 8-inch springform pan coated with cooking spray.
Bake at 350° for 25 minutes or until cake springs back when lightly touched in center. Cool 10 minutes in pan on a wire rack. Remove sides of pan. Cool completely. Sprinkle cake with powdered sugar. Serve with Lemon Cream Sauce.