Step 1

Preheat oven to 350 degrees. Butter and flour a 5-by-9-inch loaf pan. In a medium bowl, whisk together flour, baking soda, and salt.

Step 2

In a large bowl, using an electric mixer, beat butter and sugar on medium-high until fluffy, 3 minutes. Add eggs, one at a time, beating well after each addition and scraping down bowl as needed.

Step 3

Beat in bananas, sour cream, and vanilla. Beat in flour mixture and chocolate on medium. Pour batter into pan. Bake until a skewer inserted in center of loaf comes out clean, 50 to 60 minutes.

Step 4

Let bread cool in pan 10 minutes. Remove bread from pan and let cool completely on a wire rack.