What you need
2-3 very ripe bananas
1/3 cup melted butter
1 cup of sugar (can easily use 3/4 cup, or drop it down to 1/2 cup if you want it less sweet)
1 egg
1 teaspoon vanilla extract
1 teaspoon baking soda
Pinch of salt
1 cup of all-purpose flour
1/2 cup coconut flour
Or 1 1/2 cups of all purpose

What you do
Preheat the oven to 350°F
Butter and flour  a 4×8-inch loaf pan. (I use a stoneware bread pan)
In a mixing bowl, mash the ripe bananas with a fork until smooth.
Stir the melted butter into the mashed bananas.
Mix in the baking soda and salt.
Stir in the sugar, egg, and vanilla extract.
Mix in the flours.
Pour the batter into prepared loaf pan.
Bake for 1 hour to 1 hour 10 minutes (check at 50-55 minutes), or until a tester inserted into the center comes out clean.
Remove from oven and cool completely on a rack.
Remove the banana bread from the pan.
Slice and serve.