1/2 cup butter, softened
1 cup brown sugar
2 eggs
1 tablespoon vanilla extract
4 very ripe bananas, mashed
2 cups all-purpose flour
3 teaspoons baking powder
1/2 teaspoon salt
1/2 cup chopped walnuts
Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 9x5 inch loaf pan.

In a large bowl, cream together the butter and sugar until light and fluffy. Stir in the eggs one at a time, beating well with each addition. Stir in vanilla and banana. In a separate bowl, sift together flour, baking powder, and salt.

Blend the banana mixture into the flour mixture; stir just to combine. Fold in walnuts. Pour batter into prepared pan.

Bake in preheated oven for 1 hour, until a toothpick inserted into center of loaf comes out clean.