- With the rack in the middle position, preheat the oven to 180 °C (350 °F). Line three 23 x 13-cm (9 x 5-inch) loaf pans with parchment paper, letting it hang over two sides. Butter the other two sides.
- In a bowl, combine the flour, baking powder, and baking soda. Set aside.
- In another bowl, cream the butter and sugar with an electric mixer. Add the eggs and vanilla and beat until smooth. On low speed, add the bananas and dry ingredients alternately with the sour cream.
- Spread half the batter into the loaf pans. Sprinkle with half the brown sugar and chocolate chips. Cover with the remaining batter and top with the remaining brown sugar and chocolate chips. Bake for about 55 minutes or until a toothpick inserted in the centre of the bread comes out clean, but slightly topped with melted chocolate.