In a stand mixer or a large bowl with a hand mixer, beat first four ingredients (brown sugar through eggs) on medium speed until well mixed.
In a separate bowl, mash together bananas, oats, and milk until well blended. Add to the sugar mixture.
In a separate large bowl, whisk together flour, baking powder, baking soda, salt and cinnamon.
Add dry ingredients to the wet mixture in the mixer and beat on medium speed until just combined. Stir in ½ cup chocolate chips.
Add batter to 9 x 5-inch loaf pan coated with cooking spray or lined with parchment paper.
Sprinkle remaining chocolate chips evenly over the batter.
Bake at 350°F for 45 to 55 minutes, just until the middle is solid and a toothpick inserted into the center comes out clean. Allow to cool for at least 5 minutes on a rack before slicing and serving.
Notes
Storage tips: wrap banana bread in plastic wrap or parchment paper, or place in a large airtight food storage container and refrigerate for up to 5 days. You can also freeze banana bread for up to 2 months.