Brown the Butter

1. In a large skillet (preferably a light colored one to make it easier to see the color of the butter as it browns), melt butter over medium heat, stirring constantly.
2. Once the butter is completely melted, it will start to foam. Continue stirring constantly. After about 6-8 minutes, the butter will start to brown. Look for deep brown specs (if you see a lot of black specs, the butter is burned and you'll have to start over). It will also have a very pleasantly nutty aroma.
3. Once this happens, pour the browned butter into a large, shallow container (a baking dish works well). Place in the fridge and let it cool completely (this can take a couple hours).

Make the Cookie Dough

1. In a medium bowl, sift together flour, baking soda, sea salt, and corn starch. Set aside.
2. In a large bowl, cream together cooled browned butter and sugars. Add the egg, egg yolk, and vanilla extract. Whisk until thoroughly mixed.
3. Stir the flour mixture into the sugar mixture until thoroughly combined.
4. Gently fold in chocolate chunks and toffee bits.
5. Cover the bowl with plastic wrap and chill dough for 30 minutes. Preheat oven to 350˚F. Prepare a baking sheet with a silpat or parchment paper
6. After chilling, scoop out balls of dough, about 2 tablespoons each, onto the prepared baking sheet.

Bake and "Pan Slam" the Cookies

1. Bake 10-12 minutes (depending on your oven). At the 8 minute mark, remove the tray from the oven and "slam" it down on your stove top a couple times. Place it back in the oven and cook for 30 seconds, then remove the pan and slam it again a couple times. Repeat this one more time: cooking for 30 seconds and slamming.
2. Remove the cookies from oven when they look almost but not quite done. They will still be soft in the center. Let pan cool on a wire rack for 10 minutes. Remove cookies from the pan and let cool. Garnish with finishing salt as desired.