Ingredients

• 1 1/4 cups (280 grams) unsalted butter
• 1 pound (450 grams) dark chocolate, roughly chopped
• 1 1/2 cups (230 grams) cake flour
• 2 cups (275 grams) all-purpose flour
• 1 teaspoon (5 grams) kosher salt
• 2 teaspoons (8 grams) cornstarch
• 1/2 teaspoon (6 grams) baking soda
• 1 1/4 cups (285 grams) light brown sugar
• 1/2 cup (115 grams) white granulated sugar
• 2 eggs
• 3 egg yolks
• 2 cups (165 grams) rough-chopped walnuts