To brown the butter, add the butter to a pan over medium low heat. Stir while the butter starts to melt. The butter will start to bubble, then after a couple minutes it will start to foam up — keep stirring. After the foam subsides, you'll have brown, nutty smelling butter! Take the pan off the heat and pour the butter into a glass bowl or cup. Add the ice cube to the butter and stir while the water melts. This brings back moisture that evaporated while the butter cooked. Let the butter cool off to room temperature. If you are in a hurry you can put it in the fridge or freezer to speed up the process.

When the butter has cooled, add it to a bowl with the brown sugar and white sugar. Using a stand mixer or hand mixer, mix for 2-3 minutes until it is light and fluffy.

Add the eggs and vanilla extract. Mix until combined.

Add the flour, cornstarch, baking soda, and salt. Mix until just combined.

Add the chocolate. If you are using chocolate bars, chop the bars into small pieces before adding. Reserve a few larger chunks of chocolate for later. Mix until the chocolate is evenly spread through the dough.

Using a large cookie scoop, scoop the dough onto a plate or a piece of parchment paper. Press one reserved large chunk of chocolate onto the top of each dough ball. Sprinkle with a bit of flakey salt (optional, but very good).

Transfer the dough balls to the fridge and let them chill overnight. If you are in a hurry you can chill the dough for 30 minutes to 2 hours, but overnight is best. Please see the pictures and text above to see the difference in chill times.

Preheat the oven to 350 F. Transfer up to 6 dough balls to a lined or lightly greased baking sheet. Bake for 10-12 minutes, until the edges of the cookies are just starting to brown. Eat them hot or let them cool and enjoy!

Keep any extra cookies in a sealable container. They do not have to be kept in the fridge.