In the bowl of a stand mixer, add butter and confectioners' sugar. Beat on medium until creamy.

Add vanilla, and mix until incorporated.

In a separate bowl, add flour, cornstarch, and salt.

With the mixer on low, add in flour mixture, one cup at a time.

Gently fold in ¾ cup toffee bits (reserving ¼ cup for topping).

Add dough to a lightly floured work surface and roll into a 6-inch log, about 3 inches in diameter. Wrap in plastic and seal the ends. Place in refrigerator for 1 hour.

Preheat oven to 350°F. Line baking sheets with parchment paper.

Remove dough from fridge, slice into ¼-inch cookies, and place on baking sheets about 1 inch apart. Top with reserved toffee bits.

Bake for 10-12 minutes until lightly browned.

Cool on wire racks for 5 minutes before transferring.