Preheat oven to 350 degrees F. Grease bottom and 1/2 inch up the sides of one 9x5x3-inch loaf pan; set aside. In a large bowl combine flour, baking powder, baking soda, cinnamon, salt, nutmeg, and ginger. Make a well in center of flour mixture; set aside.

In a medium bowl combine eggs, mashed bananas, sugar, and oil. Add egg mixture all at once to flour mixture. Stir just until moistened (batter should be lumpy). Fold in walnuts. Spoon batter into prepared pan. If desired, sprinkle Streusel-Nut Topping over batter.

Bake for 55 to 60 minutes or until a wooden toothpick inserted near center comes out clean (if necessary, cover loosely with foil the last 15 minutes to prevent overbrowning). Cool in pan on a wire rack for 10 minutes. Remove from pan. Cool completely on rack. Wrap and store overnight before slicing. Makes 1 loaf (16 slices).

In a small bowl combine brown sugar and flour. Using a pastry blender, cut in butter until mixture resembles coarse crumbs. Stir in chopped walnuts.