In a small bowl, whisk together flour, cornstarch and salt and set aside.

In a large mixing bowl, beat butter and sugar until light and fluffy. Add the caramel flavoring and beat until blended. Add the dry ingredients and beat just until blended.

Wrap the dough in plastic wrap and refrigerate for at least an hour.

Preheat oven to 350°. On a lightly floured surface, roll out the dough to ¼th inch thickness. Cut with a fluted 2 inch round cookie cutter. Place the cookies 1 inch apart on baking sheets lined with parchment paper or Silpats.

Bake 10-12 minutes or until edges are lightly browned. Allow cookies to cool 5 minutes on baking sheet then transfer to wire rack to cool completely.

Add chocolate and shortening to a small, deep microwave safe dish. Microwave on 50% power for 1 minute. Stir and repeat until chocolate is melted and smooth.

Dip one side of the cookie in the melted chocolate. Let excess chocolate drip back into bowl. Sprinkle toffee pieces on chocolate and place on baking sheet lined with parchment or Silpat to dry completely about 2 hours.