Preheat your oven to 350℉ and line a cookie sheet with parchment paper.
Cream together butter, sugar, and brown sugar until light and fluffy. Scrape down the sides of the bowl.
Add the egg and vanilla and mix until fully incorporated.
In a separate bowl, add the flour, baking soda, and cornstarch. Whisk to combine.
Add the flour mixture to the butter mixture and mix just enough to combine.
Add the toffee bits and fold them into the cookie batter.
Using a cookie scoop, scoop out the dough onto the parchment-lined cookie sheet.
Place the cookies on the middle shelf of the preheated oven and bake for 8-10 minutes or until the cookies set and edges brown slightly.
Remove the cookies from the oven, allow to cool on the pan for about 2 minutes. Then transfer the cookies to a cooling rack. Enjoy!
