Preheat oven to 300°F (150°C). Grease four 7×3-inch loaf pans.
In a large bowl, cream the butter and sugar. Add the eggs, mashed bananas, sour cream, vanilla, and cinnamon and stir to combine. Add the salt, baking soda, cocoa powder and stir until just combined. Fold in the nuts and chocolate chips. Divide the batter between the prepared pans.
Bake the loaves for 1 hour or until a toothpick inserted in center comes out clean.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.