Melt the butter in microwave and set aside to cool.
Separate the eggs.
In a large bowl, place the egg yolks with sugar and salt and beat with a hand mixer until creamy. Set aside.
Separate, mix the nuts with the flour.
Chop the bananas small and add them to the egg yolks.
Add the melted butter, buttermilk and flour mixed with nuts.
Beat the egg white stiff, for about 5minutes.
Add the egg whites to the mixture, folding them gently into the batter and careful to not lose the air.
Divide batter evenly over 12 muffin cups.
Bake the muffins on the middle rack of the oven for about 25-30 minutes or until golden brown on top and a toothpick inserted in the middle of one of the muffins comes out clean.
Remove from the oven and cool the muffins on a metal rack.