In a big pot, melt the butter without salt over low heat.
After the chocolate is melted, put in the small marshmallows and keep stirring until they are completely melted and smooth.
Take the pan off the stove and add the Rice Krispie cereal.
Use a spatula or wax paper to mix the cereal with the marshmallow mixture until everything is well covered.
Press the layer of Rice Krispies for 2 minutes.

Put oil or butter on a baking dish that measures 9 by 13 inches.
Spread the Rice Krispie mixture evenly in the pan. You can use a spatula or wax paper to spread and press down the mixture.
Allow the Rice Krispie layer to cool down and harden completely at room temperature.

Make the banana pudding layer (3 minutes):

In a bowl, mix the instant banana pudding powder with cold milk for 2 minutes until it thickens.
Carefully mix the cut bananas into the pudding.
Gather and relax (2 hours):

Once the Rice Krispie layer has hardened, evenly spread the banana pudding mixture on top.
Put a lid on the baking dish and place it in the refrigerator for at least 1 hour, or until the pudding layer becomes solid. For best results, let it cool for 2 hours.
Serve and have fun!

Cut the Banana Pudding Rice Krispie Treats into square pieces before serving.
If you want, add a small amount of whipped cream on top of each square before serving.