Preheat oven to 350 degrees F. Grease a 7x11 inch rectangular baking dish. Mash the bananas in a large bowl.
Next, add the milk, peanut butter, egg, and vanilla. Whisk to combine.
Add the rolled oats, baking powder, cinnamon and salt and mix until combined.
Fold in the chocolate chips until evenly distributed.
Pour the oatmeal mixture into the prepared baking pan. Spread it around with a spoon or spatula until evenly distributed. Sprinkle with additional chocolate chips, if desired.
Place in the oven and bake for 40-50 minutes or until an inserted toothpick comes out clean. Allow to sit for at least 30 minutes before cutting to allow it to firm up.
To serve, top with additional banana slices and a drizzle of peanut butter, if desired.