Mix cake mix as directed. Pour half of the batter into a greased 9x13 pan. Bake in preheated 350 degree oven for 15-20 minutes. Melt caramels, butter and milk together. Pour over baked mixture. Sprinkle chocolate chips and nuts over caramel mixture. Pour remaining cake batter over top of all and bake 20 minutes at 250 degrees then 10 minutes at 350 degrees.