Blend together butter, eggs, syrup, vanilla and vinegar.
Add in flour, baking soda, salt & cinnamon and blend till combined.
In a separate bowl, mash bananas, add milk and stir.
Add banana mixture to mixing bowl and blend together.
Line mini muffin pan with liners and fill 3/4 full with mixture.
Bake at 350 for 15 minutes, till toothpick comes out clean.
Cool on wire rack before serving.