Prepare an 8 x 8 or 9 x 9 pan with parchment paper and a light coating of baking spray.
Cook butter and peanut butter over medium heat in a medium to large saucepan until melted and combined.
Mix in 5 cups of marshmallows, stirring until melted completely. Remove from the heat and add the vanilla extract.
Add the cereal to the pan, stirring until combined. Stir in the chocolate chips and marshmallows only stirring until incorporated but not all marshmallow fully melted.
Pour the mixture into the pan and press lightly to smooth the top.