Preheat oven to 350 degrees and spray a 13x9” casserole dish with non-stick spray.
In a large bowl, mash up the bananas with a fork. Add the sugars and whisk together really well.
Add the eggs, vanilla, peanut butter, melted butter, and milk. Whisk really well until smooth.
Add the flour, salt, and baking soda. Mix until the dry ingredients are all incorporated.
Finally, add 3/4 cup of mini chocolate chips and stir.
Pour the batter into the prepared baking dish. Top with 1/4 cup of mini chocolate chips.
Bake for 25-35 minutes. Baking time will depend on thickness of your bars. Bars are done when they are springy in the middle and when an inserted toothpick comes out clean.
Let the bars cool for 15 minutes before cutting. Leftover bars can be stored in an air-tight container (or cover with plastic wrap) at room temperature for up to 5 days.