Place butter in a medium microwavable mixing bowl. Microwave butter for 30 seconds, or until half melted.
Add sugar, and mix until sugar is fully incorporated in the butter. Add bananas and mash the bananas in the bowl next to the butter/sugar. Add the egg and slightly beat it. Mix all the ingredients.
Add the flour to the bowl. Add the baking soda and salt on top of the flour. Add the vanilla (I do this now so that I don’t get the 1/4 tsp spoon wet). Mix all the ingredients together. A lumpy batter is just fine.
Spray your pie dish with non-stick spray. I use an olive oil spray. Pour the batter in the pie dish.