Borrowed from Martha Stewart. The inclusion of sour cream seems to make a difference.

Ingredients

• 1/2 cup (1 stick) butter, at room temperature, plus more for pan
• 1 cup sugar
• 1 1/2 cups unbleached all-purpose flour
• 1 teaspoon baking soda
• 1 teaspoon kosher salt
• 1 cup mashed very ripe bananas
• 1/2 cup sour cream
• 1 teaspoon pure vanilla extract
• 1/2 cup chopped walnuts or pecans

Directions

1. Preheat oven to 350 degrees. Butter a 9-by-5-by-3-inch loaf pan; set aside. In an electric mixer fitted with the paddle attachment, cream butter and sugar until light and fluffy. Add eggs and beat to incorporate.

2. In a medium bowl, whisk together flour, baking soda, and salt. Add to the butter mixture and mix until just combined. Add bananas, sour cream, and vanilla; mix to combine. Stir in nuts and pour into prepared pan.

3. Bake until a cake tester inserted into the center of the cake comes out clean, about 1 hour 10 minutes. Let rest in pan for 10 minutes, then turn out onto a rack to cool.