Preheat oven to 350 degrees. Spray a loaf pan with cooking spray.
Stir together the flour, cocoa powder, baking soda, cinnamon and salt.
In the bowl of your stand mixer, beat together the sugar and eggs until light and fluffy. Drizzle in oil and chocolate syrup. Beat in the mashed bananas, sour cream, and vanilla. Fold in dry ingredients, nuts, and chocolate chips.
Pour into the prepared loaf pan and bake for about 45 minutes to 1 hour.
(I used 3 mini loaf pans and baked them for about 30 minutes.)