Coat a 9x9" pan with cooking spray. Set aside.

In a large sausepan, melt the butter. Add the marshmallows and cook until melted. Stirring constantly. Remove from heat.

Add peanuts and both cereals . Stirring well to coat. Transfer mixture to prepared pan. And press into an even layer.

Set aside to cool. ( Helpful hint; coating the back of a large spoon with cooking spray works well when pressing cereal mixture onto pan.)..