Payday Bars Ingredients Crust: 1box yellow cake mix 2/3 c unsalted butter, softened 1 egg Mix all of the ingredients, press into a slightly greased 9X13 pan. Bake at 350 for 12-18 minutes.(I baked mine for 20-25. Until the edges were golden) Second Layer: 2 cups of marshmallows Sprinkle marshmallows over top of crust. Bake