Using electric mixer, in a medium bowl, cream butter, brown and white sugars, then egg and vanilla.
In another bowl, stir together, flour, baking soda and salt. Mix well.
Add dry ingredients to wet ingredients and mix well until a soft dough forms.
Stir in 3/4 cup of chocolate chips and 1/2 cup of coarsely chopped pecans. Mix until chocolate chips and chopped pecans are evenly distributed in cookie dough.
Press cookie dough evenly into bottom of an ungreased, 8-inch square baking pan.
Bake 28 to 33 minutes or until golden brown. Remove from oven.
Meanwhile, in a 1-quart saucepan on stove top, heat 24 caramels and 1 Tbs milk over low heat, stirring frequently, until melted and smooth. Remove from heat.
Carefully spread melted caramels evenly over warm cookie bars and sprinkle with pecan halves. Cool completely on cooling rack, about 1 hour.
In small microwavable bowl, microwave 1/4 cup of semisweet chocolate chips and 1 tsp shortening uncovered on High 30 to 60 seconds, stirring every 15 seconds, until melted and smooth. Drizzle over cookie bars. Let stand about 30 minutes or until chocolate is set.