Toffee

1. Line a baking sheet with parchment paper and set aside
2. In a small heavy sauce pan over low heat bring the butter and sugar to a boil, stirring occasionally. Bring the mixture to 285°F on a candy thermometer, the mixture will become a deep amber color. Immediately remove the pan from the heat, cool for 1 minute and spread the mixture evenly onto the prepared pan. Allow the toffee to cool completely and then using a knife, break it into small pieces.

Cookies

1. In the bowl of your stand mixer fitted with the paddle attachment beat the butter and both sugars together for 2 minutes. Add in the egg, yolk, vanilla, corn syrup, baking soda, salt and cornstarch. Mix for 1 minute on medium, or until the mixture is evenly combined.
2. Turn the mixer to low and add in the flour, mixing until just combined.
3. Stir the toffee bits into the cookie dough and chill for 1 hour.
4. Preheat the oven to 325°F and line a baking sheet with parchment paper.
5. Using a medium (2 tablespoon) cookie scoop drop the dough onto the lined baking sheet 3 inches apart. The cookie will spread while baking.
6. Bake for 11-13 minutes until the cookies are golden brown at the edges.
7. Allow the cookies to cool on the pan for 5 minutes and then transfer them to a wire rack to cool completely.