Heat oven to 350°F. Place pie crust in 9-inch glass pie plate as directed on box for One-Crust Filled Pie.
In 2-quart saucepan, melt butter over low heat; remove from heat. Stir in sugar, vanilla and eggs until well blended. Stir in flour, cocoa and salt until smooth. Stir in chocolate chunks and pecans. Spread evenly in pie crust.
Bake 45 to 50 minutes or until set. Cool 1 hour.
Meanwhile, in 2-quart saucepan, heat caramels and half-and-half over low heat, stirring constantly, until caramels are melted and mixture is smooth. Serve hot caramel sauce over each serving.