Preheat oven to 425. Spray baking sheet with nonstick cooking spray.
Beat bananas, egg whites, oil and brown sugar in a large bowl or food processor. Add flours, baking powder, baking soda and pumpkin pie spice. Mix until well blended. Let stand five minutes for dough to rise.
Scoop out heaping tablespoond og dough onto prepared baking sheet.
Using thin rubber spatula or butter knife, round out doughnut hole in center of dough.
With spatula, smooth outside edges of dough into round doughnut shape.
Repeat until all dough is used. Sprinkle with sugar and walnuts.
Bake 6-10 minutes or until tops are golden. Note: you could also make this recipe using 8 ounces of canned pumpkin in place of the banana!