Preheat the oven to 350 degrees F. Use a small microwave-safe dish, and mix the caramels and 1/3 cup milk, and microwave until it is melted for about 2 minutes.
Stir after about 1 minute. Use a large mixing bowl, and combine together the cake mix, the remaining 1/3-cup milk, and the margarine.
Spread half of the mixture in the bottom of a 13x9x2inch pan coated with nonstick cooking spray. Bake for 6 minutes, and remove from the oven and sprinkle with the chocolate chips.
Evenly pour the caramel over the chocolate chips, and drop the remaining cake mixture over the partially baked layer. Keep baking for 15 minutes, or until the sides pull away from the pan. Brownies harden as it cools; do not over bake.