When able to bake, preheat oven to 350°F and line a baking sheet with parchment paper. Put aside.
In a medium bowl, combine collectively the flour, cornstarch, and salt. Put aside.
In a separate, bigger bowl, cream collectively the butter and powdered sugar with an electrical mixer. Add vanilla and blend till mixed.
Step by step add dry substances to butter combination, stirring to mix. Add butterscotch chips and toffee bits and stir.
Lay a sheet of plastic wrap onto a countertop or work floor. Place dough on high of plastic wrap and kind right into a log about 2.5 inches in diameter. Wrap and chill till agency, 1 to 2 hours.
Unwrap dough and reduce into 1/4-inch slices. Prepare slices 2 inches aside on ready baking sheet and bake till frivolously browned on edges, 10-12 minutes.
Let cool on sheet 2 minutes earlier than eradicating to a wire rack to complete cooling. Get pleasure from!