Mix together the cake mix, butter and 1/3 cup evaporated milk. Spread half of this mixture in a 13x9-inch pan. Bake for 6 minutes at 350 F. Sprinkle the chocolate chips and nuts on top of the baked mixutre. Melt caramels in milk. Drizzle over the nuts and chocolate chips. Pat remaining batter on top of this. Bake for and additional 20 minutes.