Start by greasing a 9×13-inch pan with a bit of butter or cooking spray to ensure easy removal of the treats later.

In a large saucepan, melt the butter over low heat. Once the butter is melted, add the miniature marshmallows and stir constantly until they are fully melted and smooth.

Remove the saucepan from the heat and quickly add in the Rice Krispies. Stir gently but thoroughly until the cereal is completely covered with the marshmallow mixture.

In a separate mixing bowl, combine the instant banana pudding mix with the milk. Whisk vigorously until it thickens.

Stir the banana pudding into the Rice Krispies mixture. Ensure everything is well-combined. Pour the mixture into the prepared pan and press it down firmly with a spatula to create an even layer.

Allow the treats to cool at room temperature, about 30 minutes. If desired, top with whipped cream and banana slices before cutting into squares.