Preheat oven to 350 degrees. Butter the bottom and sides of a 9X13 inch metal baking pan. Put a long piece of parchment paper in the bottom of the pan, letting the parchment extend up two sides of the pan and overhang slightly on both ends. (This will make it easy to remove the bars from the pan after they have baked.) Butter the parchment.
Place cookies in a food processor fitted with the metal blade. Pulse cookies until fine crumbs form. Add melted butter, process until crumbs clump together.
Press crumbs into prepared pan. Bake 15 minutes or until golden brown.
While the base is baking, melt the peanut butter chips, corn syrup, butter, and vanilla in a saucepan over medium-low heat, stirring until smooth, about 5 minutes.
Spread ½ cup of the peanut mixture over crumb base. Top with marshmallows and return the pan to the oven. Bake until marshmallows puff up, about 2 minutes, then remove from oven. (DO NOT let the marshmallows brown or they will turn crunchy.)
In a large bowl, toss peanuts and cereal with the remaining peanut mixture to coat.
Drop spoonfuls of the topping over the marshmallows, then press and spread evenly with a spatula sprayed with non-stick cooking spray to prevent sticking). Cool bars completely before cutting into squares.