No need for mixer in this recipe. Preheat the oven to 350F. With a wooden spoon, mix butter into the mashed bananas in a large missing bowl. Mix in the sugars, egg, vanilla, oats, and yogurt/sour cream. Sprinkle bakin soda and salt over the mixture and mix in. Add the flours last, mix. Pour mixture into a buttered 4x8 inch loaf pan. Bake for 1 hr. Check for doneness. Cool on rack. Remove fr.o.m. Pan and slice to serve.