Melt butter over medium heat. Swirl the pan occasionally to be sure the butter is cooking evenly. As the butter melts, it will begin to foam. The color will progress from lemony-yellow to golden-tan to, finally a toasty-brown. Once you smell the nutty aroma, take the pan off the heat and transfer the browned butter into a heat-proof bowl to cool.

Put the peeled bananas into a large mixing bowl and smash with a wooden spoon. Add the melted butter and mix together with the spoon.

Add the sugars, egg, and vanilla, stirring to combine.

Add the flour last and mix.

Pour mixture into a buttered 4x8" loaf pan.

Sprinkle generous amounts of turbinado sugar on top of the mixture in the loaf pan.

Bake for one hour. Cool on rack before removing from the pan to serve.