bowl mix sugar, mayonaise and vanilla until well blended. Stir in flour mixture and add 1/2 cup pecans. (dough will be thick and sticky.) Press into well greased 8 inch square baking pan. Sprinkle with remaining nuts and press into dough. Bake in 350 degree F oven 15 minutes or until pick inserted in center comes out clean. Cool in pan on rack. Cookies are soft while hot but firm when cool. Cut into about 12 squares.