Preheat the oven to 350 degrees.
Put all the wet ingredients into the bowl of your stand mixer—bananas, sugar, butter, eggs, vanilla, and milk. Mix until it’s all combined, although you may see chunks of bananas. If needed, you can use a potato masher to get out all of the bigger clumps.
Mix the dry ingredients in a separate bowl—flour, baking soda, baking powder, salt, and cocoa powder.
Add the dry ingredients to the wet ingredients a little at a time.
Add the chocolate chips, if using.
Spray two loaf pans with cooking spray and divide the batter evenly between them.
Cook for 65-75 minutes, or until a knife inserted in the center comes out clean.
Let cool in the pans for 5-10 minutes, then carefully put them on a wire rack to finish cooling.
If freezing, wait until they are completely cool and then wrap in plastic wrap, then foil.