Preheat the oven to 350°F. Spray one large 10 x 5-inch loaf pan or two standard 8 x 4-inch loaf pans with baking spray. Set aside.
In a medium-size mixing bowl using a whisk, sift together flour, granulated sugar, brown sugar, baking powder, baking soda, salt and cinnamon.
In a separate bowl, whisk together banana, buttermilk, butter, vanilla and eggs.
Add the wet ingredients to the dry ingredients mixing with a large non stick spatula or spoon, until fully combined. Mix chocolate chips into the batter until evenly distributed. (You may reserve ¼ cup to sprinkle on top, if desired)
Pour batter evenly into pan. Bake for 50-60 minutes for a large 10 inch loaf pan or 40-45 minutes for two medium-size loaf pans. Bake until a toothpick inserted into the center comes back clean.
Cool in loaf pan for 10 minutes then remove to a cooling rack to cool completely.
Store in an airtight container chilled or at room temperature.