Ingredients

1/2 cup (1 stick) butter, at room temperature, plus more for pan

1 cup granulated sugar

2 large eggs

1 1/2 cups unbleached flour

1 teaspoon baking soda

1 teaspoon salt

1 cup mashed very ripe bananas

1/2 cup sour cream

1 teaspoon vanilla

1/2 cup chopped walnuts or pecans

Preparation

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. 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. 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.