Spray a 9x13 casserole dish with non-stick spray.
Add melted butter to the bottom of the dish, then place slices of bread to cover the bottom.
Add slices of banana on top of the bread, then sprinkle ½ cup chocolate chips.
Make another layer of bread, banana and chocolate chips. Set aside.
In a medium mixing bowl (it is easier to use one with a spout) add milk, eggs, vanilla and ground cinnamon. Whisk until combined.
Pour over top, ensuring to get all the bread wet. Cover with foil and set in the fridge for at least 3 hours or overnight.
When ready to bake, remove from the fridge as the oven preheats to 325F.
Lightly spray the inside of the aluminum foil with non-stick spray, then bake covered for 45 minutes, then increase the heat to 375F. Once the oven has reached 375F, then carefully remove the tinfoil and bake for an additional 10–15 minutes, or until the top starts to get golden brown.
Cool slightly and serve warm.