My mom stumbled across this recipe when I was in grade school. I'll occasionally make these and bring them into work where everyone refers to them as "special brownies". I also make them for family BBQs and my niece and nephew's birthdays and they never last.
Preheat oven to 350. Grease and flour 9x13" pan. Prepare cake mix according to the directions on the box. Unwrap caramels and put into top pan of a double boiler with the margarine and evaporated milk.
Put half the prepared cake mix into the pan and bake it for 10-15 minutes, or until the cake is set. While cake is baking melt caramels, etc in double boiler until smooth. Once mixture is smooth add pecans. (do not add too soon or pecans will soften)
Remove the cake from the oven and pour caramel and nut mixture over cake, spreading it around until all the cake is covered.
Put chocolate chips on caramel-nut mixture.
Pour remaining cake batter over the cake, and spread it around to cover all the caramel and chocolate chips
Put cake into the oven and bake 10-15 minutes, or until the cake is cooked through.