Preheat oven to 350°F
Mash the bananas in a bowl. Add the egg and butter.
Put all the dry ingredients together into a fine mesh sieve or sifter and sift into the bowl. Mix well with a wooden spoon.
Bake in a buttered loaf pan until a toothpick stuck into the bread comes out clean, 55 to 60 minutes.
Slice and serve.