In a bowl, mix butter, sugar and the eggs together.
Add in baking powder, baking soda, salt and 1 cup flour. Mix well.
Add in the additional 1 cup flour and mix well.
Now add in the bananas and the vanilla extract. Again mixing well.
Spray the inside of the crock-pot with cooking oil.
Add the batter to the crock-pot.
Cover and Cook on LOW for 4 hours or until a toothpick inserted into the middle comes out clean.