In a small bowl, whisk the flour and salt together. Set aside.
In the bowl of a stand mixer, beat the butter and powdered sugar until smooth and creamy, about 3 minutes. Beat in the vanilla extract. Slowly add in the flour mixture and mix until just combined. Stir in 1/2 cup of the toffee bits. Form the dough into a disk shape and wrap in plastic wrap. Chill the dough for at least 1 hour or until firm.
When ready to bake, preheat oven to 350 degrees F. Line a large baking sheet with parchment paper or a Silpat baking mat and set aside.
On a lightly floured surface, roll out the dough into a 1/4 inch thick square. Cut into squares, rounds, or shape of your choice using a lightly floured
cookie cutter. Place shortbread cookie son the prepared baking sheet and bake for 15-18 minutes, or until cookies are very lightly browned around the edges. Remove cookies from baking sheet and cool completely on a wire cooling rack.
Put the chocolate chips in a microwave safe bowl and melt, stirring every 30 seconds until melted. Dip the shortbread cookies in the melted chocolate and sprinkle with additional toffee bits. Lay on a piece of parchment paper or wax paper to set up. Once chocolate is completely dried, store cookies in an air tight container for up to 5 days.