Having baked an apple cake yesterday, I saw that I had some over-ripe and blackened bananas in the fruit bowl, and in a cake-baking mood, I decided to bake a banana cake with the little butter I had left,  I subsisted the dairy with sour cream (which was going off anyway, having been sitting around in the fridge for quite a long time):

I only had about 100g of butter left, so I used 100g (less a little for greasing the loaf tin)   1/2 cup sour cream
2 large eggs
3/4 cup organic brown sugar
1 1/2 cups unbleached flour
1 teaspoon baking powder
1 teaspoon salt
4 large ripe bananas
1 teaspoon pure vanilla extract

Preheat the oven to 350 degrees. Grease a loaf tin. Cream the butter and sugar until light and fluffy. Add the rest of the ingredients and mix thoroughly.  Pour into the loaf tin and bake for about 1 hour until the insides are no longer sticky when poked with a fork.

Very yummy indeed.

(I served mine with ice cream and drizzled with dulce le leche)