Prepare a standard muffin tin with liners or spray lightly with non-stick cooking spray.
In a large bowl beat the butter and sugar together well.
Add the eggs, bananas and buttermilk and mix to combine.
In a separate bowl, stir together the flour, baking soda and salt; add to banana mixture along with bran cereal and stir just until moistened.
Divide the batter evenly between the muffin cups.
Bake at 350° for 16-22 minutes or until a toothpick comes out clean. Cool for 5 minutes before removing from pans to wire racks.
