Melt part of the milk chocolate with the butter. When almost melted, remove from heat and stir until smooth, then stir in the rice cereal a bit at a time and combine. Spoon the Rice Krispie mixture evenly on top of the first layer.
Melt the remaining milk chocolate, then pour on top of 2nd layer, swirl to cover. Let sit for at least 2-3 hours in the fridge. Then cut into bars.