Step 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.

Step 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.

Step 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.