In a large mixing bowl, stir together Honey Nut Cheerios, peanuts, and cranberries. Set aside.
In a saucepan, melt butter and marshmallows over low heat, stirring until smooth. Stir in peanut butter. Pour the marshmallow mixture over the Honey Nut Cheerios mixture and gently stir to make sure everything is coated.
Transfer to a 8x8-inch dish and spread the mixture to the corners. Let set before cutting and serving.