Note: use only real margarine (80% fat) or butter; lower-fat spread products may not produce best results. Preheat oven to 350 degrees. Beat margarine, applesauce, eggs, milk and brown sugar in large mixer bowl until smooth. Add bananas and blend at low speed; beat at high speed 1 to 2 minutes. Combine flour, baking powder, baking soda and salt; mix into batter. mix in walnuts. Pour batter into greased 8-by-4 inch loaf pan. Bake until bread is golden and toothpick inserted in center comes out clean, 55 to 60 minutes. Cool in pan on wire rack for 10 minutes; remove from pan and cool to room temperature.