To melt the butter, use a medium-sized saucepan. Set the heat to low or medium-low until the butter has fully melted. Once melted, set the butter aside to cool.
To combine all of the dry ingredients together, use a medium-sized bowl. Add the all-purpose flour, cake flour, corn starch, baking soda, and salt. Whisk to combine.
In the stand mixer with a whisk attachment, add the light brown sugar and white sugar. Set the whisk to medium speed to combine. Then, slowly add the melted butter to whisk together with the two sugars.
In the stand mixer containing the combined mixture of sugars and butter, keep the whisk speed on medium. First, add in the eggs. Allow it to mix with the other ingredients. Then, add in the egg yolks. Whisk until the mixture is smooth.
The mixture inside the stand mixer bowl should be smooth and thoroughly combined. If so, change the stand mixer attachment to the paddle.
Now it is time to add the dry ingredients mixture in the medium-sized bowl to the stand mixer bowl with the paddle attachment on. On medium speed, whisk until fully combined and smooth.
With the Chef’s knife, chop the chocolate on the cutting board. Add the chopped chocolate and walnuts (optional) to the standing mixer bowl with the other ingredients. Mix.
Either in the standing mixer bowl or in the medium-sized bowl, cover the dough, and set in the refrigerator. Allow the dough to chill for 45-60 minutes.
Before placing it on a parchment-lined baking sheet, it’s time to weigh the dough. Shape and size the dough into balls. Using the food scale, aim to have each dough ball weigh 6 ounces. Place on the parchment-lined baking sheet.
The oven should be preheated at 425 F. Place the baking sheet with cookie dough balls in the oven to cook for 10-14 minutes.
Pull the cookies out of the oven, allowing them to cool on a wire rack before serving. Enjoy!