Heat oven to 350°F. Grease or spray bottom of 11x7-inch pan. Make and cool brownies as directed on box, using 11x7-inch pan. Cut into 24 rectangles.
Place taco shells on microwavable plate. Fan out in a circular pattern, overlapping edges slightly. Microwave uncovered on High about 45 seconds or until warm.
Place 2 brownies in each taco shell, then top with whipped topping, pecans and caramel sauce.