Ingredients

Method

1. 1

   Combine 1/2 cup unsalted butter and 1 cup light brown sugar in a saucepan over medium heat.

2. 2

   Once the butter melts, whisk consistently to combine with the sugar. Bring the mixture to a bubble.

3. 3

   Continue whisking as the mixture cooks. Using a candy thermometer, cook until it reaches 300°F (149°C), which should take about 8 minutes.

4. 4

   Remove from the heat and immediately pour the hot toffee mixture onto a silicone or parchment-lined baking sheet.

5. 5

   Quickly spread the toffee into a thin, smooth slab using a spatula. Let it cool for about 20 minutes until completely hardened.

6. 6

   Once hard, use a mallet, the back of a spoon, or your hands to break the toffee slab into small, bite-sized pieces. Set aside.

7. 7

   Melt 1 cup of unsalted butter in a saucepan over medium heat. Continue cooking, swirling occasionally, until the milk solids turn a nutty brown color and it smells fragrant.

8. 8

   Transfer the browned butter to a heatproof measuring cup. Add the 2 tablespoons of water to bring the total liquid volume back up to 1 cup. Let the brown butter cool to room temperature, which will take about 30 minutes.

9. 9

   In a separate small bowl, whisk together the flour, salt, and baking soda. Set aside.

10. 10

    In a large bowl, add the dark brown sugar and white sugar.

11. 11

    Pour the cooled brown butter over the sugars. Whisk vigorously until the mixture is smooth and fully combined.

12. 12

    Whisk in the vanilla extract and espresso powder.

13. 13

    Add the large egg and egg yolk to the bowl and whisk until just combined.

14. 14

    Add the dry flour mixture to the wet ingredients.

15. 15

    Gently fold the ingredients together with a spatula until no dry streaks of flour remain and a dough has formed.

16. 16

    Add the semi-sweet chocolate chunks, dark chocolate chunks, and the prepared toffee bits to the dough. Mix with the spatula until evenly distributed.

17. 17

    Using a 3-tablespoon cookie scoop, portion the dough onto a parchment-lined plate or baking sheet. This should yield about 14 cookies.

18. 18

    Cover the cookie dough balls and place them in the freezer to chill for at least 3 hours, or overnight.

19. 19

    When you are ready to bake, preheat your oven to 350°F (175°C).

20. 20

    Arrange the frozen cookie dough balls on a parchment-lined baking sheet, leaving space between them to spread.

21. 21

    Bake for 15 minutes, or until the edges are golden brown.

22. 22

    Remove from the oven. If the cookies have spread unevenly, you can use a round cookie cutter or the rim of a glass to gently nudge the edges back into a perfect circle while they are still hot.

23. 23

    Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely. Sprinkle with flakey salt while they are still warm. Enjoy