Mix chocolate chips and marshmallow creme in separate bowl. Mix butter, evaporated milk and sugar in heavy 3-quart saucepan. Cook over low heat until mixture comes to a low boil. Boil for 5 minutes. Occasionally wash down sides of pan with pastry brush dipped in cold water to return sugar crystals to mixture. Add chocolate mixture to saucepan with hot sugar mixture. Add salt, vanilla and nuts. Pour into 9 x 9 inch pan or cookie tin, then let cool. Yields 1 (9 x 9-inch) pan.