Line a baking sheet with parchment paper and set aside.
In a medium pan over medium high heat, melt butter.
Add sugar, water, and salt.
Cook stirring constantly until candy thermometer reads 300 (hard crack stage).
Pour onto prepared baking sheet.
Cool until hard.
In microwave safe bowl, combine chocolate chips and shortening.
Melt this in the microwave, cooking and stirring in 30 second intervals until fully melted and thin.
Pour melted chocolate over the cooled toffee and spread to even layer.
Before chocolate cools, spread pecan pieces evenly over chocolate and gently press in.
Let stand on counter for several hours of refrigerate for 30 minutes.
Crack into bite-size pieces.