Toast pecans over moderate heat then reserve. Place pie shells on a small tray. Soften ice cream in microwave on high for 20 seconds. Fill pie shells with ice cream, mounding each shell up. Smooth edges of the ice cream pies and freeze 20 minutes to set. Remove lid of the caramel sauce and warm it, 1 minute on high. Top pies with caramel sauce and lots of toasted pecans and whipped cream.