Preheat oven to 400 degrees. Grease 8 extra large muffin cups or 15 standard muffin cups.
Beat together butter and sugar at medium speed until light and fluffy. Add eggs, one at a time, beating well after each addition. Beat in bananas until smooth.
Mix together flour, salt, baking powder and baking soda.
Alternately stir flour mixture and buttermilk into egg mixture until dry ingredients are just moistened.
Stir in nuts and vanilla. Do not overmix batter. It should not be completely smooth.
Spoon batter into either of the prepared pans, filling cups 2/3 full. Bake until lightly golden, 23 to 25 minutes for larger cups and 15 to 18 minutes for the standard size cups. Transfer pan to a wire rack to cool slightly. Turn out onto rack. Serve warm. Makes 12 muffins. Enjoy!