Cut the butter into slices (roughly Tablespoon slices.) It doesn't have to be perfect. Over medium-low heat, in preferably a a light-colored bottom (so you can see the butter brown), start melting the butter.

Stir occasionally to ensure that the butter is browning evenly. Once the butter is melted, you'll see that it will start to foam up. You'll see that light brown specks begin to form at the bottom of the pan. Once the butter begins to turn tan, remove from the heat and place on a cool surface. If your butter is extremely dark, it is burnt. You'll need to start over.

The time typically takes around 6-7 minutes, but that depends on your pan and stove. For me, it took 5 minutes. Once browned, allow the butter to slightly cool before moving on.

In a medium bowl, combine the flour, cornstarch, salt and baking soda. Set aside.

In a large bowl, combine the sugars and whisk in the slightly cooled butter. Add in the egg and egg yolk, making sure they are whisked in before adding the next. Next, add the vanilla. Using a wooden spoon or spatula, slowly mix in the flour mixture until just combined. Fold in the chocolate chips.

Mandatory step: chill the dough for at least 3 hours or up to 3 days. Do not skip this step. I chilled these cookies you see here for 24 hours. The more time you allow it to chill, the more flavor that develops.

Once chilled, take the dough out of the refrigerator and allow to slightly soften for 10-15 minutes.

Preheat the oven to 325F degrees. Line two baking sheets with silicone baking mats (preferred) or parchment paper. Set aside.

Roll the dough into balls, about 2 Tablespoons of dough for each. Place 8 total cookie dough balls on each sheet evenly apart. Bake for 10 minutes or until the edges are slightly browned. The cookies will look under baked, but that's OK. Allow the cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.

Store in an airtight container for up to 7 days (if they last that long.)

Christina's Tip: You can make cookie dough in advance and can be left in the refrigerator for up to 3 days. Or, you can freeze pre-rolled balls and bake directly from the freezer. The bake time for this is an extra minute.