Preheat oven to 350°. Bake pecans in a single layer in a shallow pan 8 to 10 minutes or until toasted and fragrant, stirring halfway through. Cool completely (about 15 minutes).
Beat butter at medium speed with an electric mixer until creamy. Stir together brown sugar and cornstarch; gradually add to butter, beating at low speed until well blended. Stir together flour and salt; gradually add flour mixture to butter mixture, beating at low speed just until blended. Add vanilla and 1 cup pecans, beating at low speed just until blended.
Turn dough out onto a lightly greased baking sheet; pat or roll dough into an 11- x 14-inch rectangle, leaving at least a 1-inch border on all sides of baking sheet.
Bake at 350° for 20 minutes or until golden brown. Remove from baking sheet to a wire rack; sprinkle shortbread with chocolate morsels. Let stand 5 minutes; gently spread melted morsels over shortbread. Sprinkle with remaining 1 cup pecans, and let cool completely (about 1 hour). Cut or break shortbread into 2- to 3-inch pieces.
I thought this was very good. The shortbread was a little dry and crunchier than I would prefer so I think next time I will bake it maybe a few minutes less, and see if that will help. But otherwise it was very good.
When I read this recipe I saw that it had butter and brown sugar which would give it a toffee-like flavor. I did not expect it to be toffee. I wanted a bark-like shortbread cookie which this is. It is delicious, packaged beautifully and everyone loved it.
These are quite good. For those claiming it "isn't toffee", you are right. The shortbread dough is toffee flavored (hence brown sugar instead of white). I am a huge shortbread fan, as I am of Scottish descent. I am picky when it comes to messing with a classic recipe. I used a good quality chocolate instead of chocolate chips and vanilla bean instead of extract. Will make again and again!