Grease a 9X13 glass pan, set aside. If using something other than glass, press parchment paper on bottom, lightly grease and finely crush up Rice Krispie cereal to line the bottom with.

For the Caramel Filling - In a medium saucepan on medium heat, heat butter and sweetened condensed milk. Unwrap caramel pieces and add. Stir frequently until combined then turn heat down to low.

For the Krispie Layer (two separate layers will be prepared) - In a large saucepan on medium heat, melt 6 tablespoons butter. Once melted, stir in 4 cups mini marshmallows and whip batter until smooth. Combine 5 cups Rice Krispie cereal and mix well until evenly coated.

Next, using piece of wax paper lightly greased, press Krispie layer down evenly into pan. Pour caramel filling over the top and spread evenly. Press about 2 1/2 cups mini marshmallows into caramel layer.

Repeat Rice Krispie layer with remaining ingredients. Heat 6 tablespoons butter and 4 cups mini marshmallows. Add 5 cups cereal and stir to combine. Press layer on top of marshmallow/caramel layer using a piece of lightly greased wax paper. Refrigerate at least 2 hours to set up.