Preheat the oven to 350°F.
Spread the chopped walnuts on a rimmed baking sheet and toast for 8 to 10 minutes, stirring halfway through.
2 cups walnuts
Remove the walnuts from the oven and allow them to cool. Increase the oven temperature to 425°F (NOT A TYPO).
While the walnuts toast, whisk together the cake flour, all-purpose flour, salt, cornstarch, and baking soda in a medium bowl. Set aside.
1¾ cups cake flour, 2 cups all-purpose flour, 1½ teaspoons salt, 1 tablespoon corn starch, ½ teaspoons baking soda
In a stand mixer fitted with a paddle attachment, cream together the cold butter, light brown sugar, and toasted or granulated sugar. Mix at medium-high speed until smooth, about 3 to 4 minutes, scraping down the sides of the bowl about every minute.
1¼ cups cold unsalted butter, 1⅓ cups light brown sugar, ½ cup granulated sugar
Once combined add in the eggs one at a time followed by the egg yolks. Then mix in the vanilla extract.
2 large eggs, 3 additional large egg yolks, 1½ teaspoons vanilla extract
Once smooth, mix in the flour mixture a little at a time until smooth.
Add in the mostly cooled chopped walnuts, chopped chocolate, and chocolate chips. Mix just until combined.
2 cups walnuts, 8 ounces chopped chocolate, 1½ cups dark chocolate chips
Weigh each dough ball out to 6oz and place on a parchment-lined baking sheet and refrigerate for 15 minutes.
Bake for 9 to 11 minutes.
Allow them to set on the pan for a couple of minutes before transferring to a wire rack to cool.