1. Melt caramels with 1/2 can of evaporated milk over low heat. Stir until smooth. Combine remaining milk with cake mix and melted margarine. Mix well. Press half of cake mixture into bottom of greased 13 by 9 baking pan. Heat oven to 350. Bake for 6 mins. Remove from oven. Sprinkle 1 cup walnuts and choc chips (if using) over crust. Top with caramel mixture, spreading to edges of pan. Top with teaspoonfuls of remaining cake mixture, pressing gently into caramel mixture. Sprinkle with remaining nuts. Return to 350 oven and bake for 20 minutes. Cool. Cut into bars.