Preheat oven to 350°F. Grease or spray with non-stick cooking spray a 9 x 5 inch loaf pan.
In a large bowl, with the mixer set on medium, cream the butter and sugar until light and fluffy, about 3 -5 minutes. Add eggs, one at a time, beating well after each addition. Add vanilla, cinnamon, sour cream. and bananas. Beat on low speed to combine.
In medium bowl, whisk together flour, baking soda and salt.
Gradually add dry ingredients to the banana mixture, beating on medium speed for one minute. Scrape down bowl as needed. Fold in chocolate chips and walnuts until well distributed.
Spread into prepared pan. Bake on center rack of oven for 1 hour to 1 hour and 15 minutes, or until toothpick inserted in center comes out clean.
Allow to cool for 10 minutes on a wire rack. Remove from the pan and cool completely on the wire rack.
Chef Tips
Reserve a handful of chocolate chips and walnuts to decorate top of bread dough before baking.Cut off a few slices of banana before mashing to arrange on top of dough prior to baking.