Line a 9x13-inch baking pan with foil, and spray the bottom and sides generously with baking spray. Set aside.

In a large pot on the stovetop, over medium heat, add the butter. Melt the butter, stirring occasionally. Once melted, add the mini marshmallows, reserving a 1/2 cup for later. Stir the marshmallows into the butter until the marshmallows are melted completely.

Remove the pot from the stove and stir in the peanut butter, vanilla extract, salt and white chocolate. Stir until all ingredients are incorporated and the white chocolate is mostly melted into the mixture.

Stir the cereal into the mixture, stirring each cup in before added the subsequent cups. When adding the last cup, add the marshmallows reserved from the bag. They will stay mostly whole.

Dump mixture out into prepared pan, pushing into an even layer. Allow treats to cool and set before adding the chocolate layer.

CHOCOLATE LAYER: Once the treats have cooled, add the chocolate chips and peanut butter to a microwave safe bowl. Microwave for 60-90 seconds, stopping every 15-seconds to stir the mixture. Remove from the microwave once the chocolate has melted. Pour the chocolate in an even layer over the cereal treats, using a rubber scraper to spread.

Allow the chocolate layer to set at room temperature for 3-4 hours before cutting into desired sized squares.