Beat butter at medium speed with an electric mixer until creamy; gradually add granulated and brown sugars, beating well. Add egg, beating until mixture is blended.
Add flour and next 8 ingredients; beat at medium speed until smooth. Pour into a greased and floured 13- x 9-inch pan.
Bake at 325° for 35 to 45 minutes or until a wooden pick inserted in center comes out clean. Cool on a wire rack. Cut into 3-inch squares. Serve gingerbread with Ginger-Molasses Whipped Cream.