Unwrap caramels and melt with milk in top of double boiler. Combine cake mix and butter according to directions on box. Pour 1/2 the batter into greased 13 x 9 inch pan and bake at 350 degrees for 10 minutes or until cake puffs up and is gooey. Pour caramel-milk mix over baked layer. Top with nuts and chocolate chips. Pour rest of batter over all and bake at 350 degrees for 25 to 30 minutes or until toothpick tests clean. Top with ice cream, if desired.