1Heat oven to 325°F. Heat taco shells as directed on box. Line cookie sheet with waxed paper.
2In 1-quart microwavable bowl, microwave chocolate chips on High 1 minute. Stir; microwave 30 seconds longer or until chips can be stirred smooth.
3Holding taco shell on bottom and with a butter knife or pastry brush, coat each shell completely -- except outer bottom edge -- with melted chocolate. Stand shells upright on cookie sheet lined with waxed paper. Refrigerate 30 minutes.
4Fill each shell with 1/2 cup ice cream. Top with caramel topping, chocolate topping and nuts. Serve immediately.