Preheat oven to 350 degrees. Grease a 9x5 bread pan and line with parchment paper.
Combine all dry ingredients. Set aside.
Beat together butter, oil, and sugar.
Once well combined add egg, vanilla, and buttermilk. Mix again until incorporated.
Add in all combined dry ingredients. Continue to mix until combined. Stir in 2/3 of the chocolate chips by hand.
Mix in mashed bananas. Stir well and then pour batter into prepared bread pan.
Sprinkle remaining chocolate chips on top and bake for 50-60 minutes.
Once top springs back bread is done. Remove from oven and let it cool on rack or oven for 20 minutes, then slice and enjoy!