Gooey Ritz Peanut Butter Cup S'mores Bars 1 box yellow cake mix 2 sleeves Ritz crackers 1 egg 1/2 cup (1 stick) butter, softened 1 (7 oz) jar marshmallow creme 1 (14 ounce) can sweetened condensed milk 2 (8 ounce) bags mini Reese’s peanut butter cups 1. Preheat oven to 350 degrees F. Line a