Prepare a large cookie sheet (preferably rimmed) by lining it with parchment paper. Set aside.
Use a large stockpot on the stove to heat butter, caramel, salt and sweetened condensed milk. Heat until the caramels are completely melted and the mixture is smooth. Heat on medium heat, stirring every 15-20 seconds.
Once the mixture is smooth, add the mini marshmallows and lower the heat to low. Continuously stir the mixture until all of the marshmallows have melted. Once the mixture is smooth again, turn off the stove heat.
Add the Rice Krispies to the stockpot and stir until all of the cereal has been evenly coated with the caramel mixture.
Immediately pour the mixture out on to the prepared cookie sheet and press it down evenly until you have reached your desired thickness for the bars. I prefer them to be 1.5-2 inches thick. Set the Caramel Rice Krispies aside while you prepare the toppings.