Cream together butter and sugar. Add in egg and beat until light and fluffy. Roughly mash the bananas with a fork and add in vanilla, greek yogurt and cinnamon. Mix into the sugar mixture.
Combine together dry ingredients: flour, baking powder, baking soda, salt and any add ins like walnuts. Fold into the wet mixture until evenly combined.
Pour mixture into a small baking pan and bake for about 45 minutes or when a toothpick inserted comes out clean.
Notes
* the banana peel should be at least 75% brown. ** if you prefer denser banana bread, reduce to 1/4 or 1/2 tsp of baking powder.