HEAT oven to 350ºF. Mix dry cake mix, butter and 1/3 cup milk until blended; press 2/3 onto bottom of 13x9-inch pan. Bake 12 to 14 min. or until center is almost set; cool 3 min. Meanwhile, mix peanut butter and remaining milk. SPREAD peanut butter mixture onto crust; top with small spoonfuls of the marshmallow creme and remaining cake mixture. Sprinkle with nuts and chocolate; press gently into cake mixture. BAKE 18 min. or just until center is set. Cool completely before cutting into bars. Nutritional InformationCalories: 190Total fat: 11 gSaturated fat: 4 gCholesterol: 10 mgSodium: 150 mgCarbohydrate: 23 gDietary fiber: 1 gSugars: 15 gProtein: 3 gVitamin A: 0% DVVitamin C: 0% DVCalcium: 2% DVIron: 4% DV