Line a 13-in. x 9-in. pan with foil and grease the foil with 1-1/2 teaspoons butter; set aside. In a microwave, melt milk chocolate chips and shortening at 70% power for 1 minute; stir. Microwave at additional 10- to 20-second intervals, stirring until smooth.
Spread half of the mixture into prepared pan. Refrigerate for 15 minutes or until firm. Set remaining chocolate mixture aside.
In a large microwave-safe bowl, melt the caramels, water and remaining butter; stir until smooth. Stir in pecans. Spread over chocolate layer.
Heat reserved chocolate mixture if necessary to achieve spreading consistency; spread over caramel layer. Cover and refrigerate for 1 hour or until firm.
Using foil, lift candy out of pan. Gently peel off foil; cut candy into 1-1/2-in. x 1-in. bars. Store in the refrigerator.