In a large bowl, whisk together the brown sugar, oil, eggs, sour cream and vanilla until smooth and well combined. Stir in the bananas until incorporated. Mix in the flour mixture just until combined. Do not over mix. Stir in the 1/2 cup of pecans if using. If using chocolate chips, set aside 1/4 cup (43g) for the top and stir in the remaining 1 cup (170g) of chocolate chips.