1Melt 1 and a quarter cup (280 grams) of unsalted butter and set aside to cool slightly.
2Rough chop 1 pound (450 grams) of dark chocolate into randomized pieces.
3In a medium-sized bowl, combine 1 and a half cups (230 grams) of cake flour, 2 cups (275 grams) of all-purpose flour, 1 and a half teaspoons (5 grams) of kosher salt, 2 teaspoons (8 grams) of cornstarch, and half a teaspoon (6 grams) of baking soda, and whisk together.
4In a stand mixer fitted with the whisk attachment, add 1 and a quarter cup (285 grams) of light brown sugar and half a cup (115 grams) of white granulated sugar.
5Whisk the sugars on medium speed and slowly stream in the cooled melted butter until creamy.
6Add two eggs one at a time, followed by three egg yolks, incorporating each egg/yolk fully before adding the next.
7Switch to the paddle attachment and mix in the flour mixture until the dough is smooth.
8Fold in 2 cups (163 grams) of rough chopped walnuts (toasting is recommended) and the chopped chocolate, preferably by hand to protect the machine.
9Wrap the cookie dough and chill in the refrigerator for at least 45 minutes; longer chilling results in taller cookies.
10Scoop 6-ounce cookie balls, making them tall, onto baking sheets lined with parchment paper. Recommend placing four cookies per tray for extra room.
11(Optional) Refrigerate the scooped cookies for an additional 25 minutes for extra height.
12Bake in an oven preheated to 425 degrees Fahrenheit (220 Celsius) for 10 to 13 minutes, or until lightly browned on the outside and slightly underdone on the inside.