Grease 8×8 baking pan. In small bowl, mix together brown sugar, margarine and cinnamon until crumbly. Add nuts and stir. Set aside. In large mixing bowl, mix together flour, sugar, baking soda, baking powder and salt. Add egg, applesauce, oil and vanilla. Stir until ingredients are wet. Pour batter into greased pan. Sprinkle brown sugar mixture over batter. Bake at 350° 20 to 25 minutes or until toothpick comes out clean when inserted in center of cake. Cool about 15 minutes.