heat oven to 350. Grease 13x9-inch pan with shortening. In small saucepan, cook caramels and milk over low heat, stirring frequently, until caramels are melted and smooth.
In medium suacepan, melt butter over low heat. Remove from heat. Add sugar, vanilla and eggs; blend well. Stir in flour, cocoa and salt; mix well. Stir in 1 1/2 cups chocolate chunks and 1 cup toasted pecans. Spoon and spread batter in pan.
Gently and evenly drizzle caramel filling over batter to prevent large pockets of caramel and to prevent caramel from reaching bottom of bars. (Caramel can cover entire surface of batter.).