Instructions

• Ensure the butter and egg are at room temperature. In the bowl of a stand mixer fitted with the paddle attachment, or in a large mixing bowl with a hand mixer (or by hand), beat the 4 ounces (115 g) salted butter, 2/3 cup (110 g) packed brown sugar, and 1/2 cup (100 g) granulated sugar until smooth and creamy, scraping down the bowl as needed.
• Beat in the 1 large room-temperature egg and 1/2 teaspoon vanilla extract until combined and uniform.
• In a small bowl, whisk together 1 1/3 cups (180 g) flour, 1/2 teaspoon baking soda, and 1/2 teaspoon flaky sea salt or kosher salt.
• Stir or fold the flour mixture into the butter mixture until just combined and no streaks of flour remain.
• Fold in 1 1/3 cups (200 g) coarsely chopped bittersweet or semisweet chocolate (including any chocolate dust) and 1 cup toasted, coarsely chopped nuts until evenly distributed.
• Cover the dough and chill in the refrigerator until firm (preferably overnight).
• When ready to bake, preheat the oven to 350°F (180°C). Line two baking sheets with parchment paper or silicone baking mats.
• Form the chilled dough into rounds about the size of a large unshelled walnut. Place the mounds evenly spaced on the prepared baking sheets. Press down the tops of each mound so they are no longer domed and the dough is even.
• Bake for 10 minutes, rotating the baking sheet midway through baking, until the cookies look about set but are not browned.
• Remove the baking sheet from the oven and quickly tap the top of each cookie with the back of a spatula, then return the sheet to the oven and bake 2 to 5 minutes more, until the tops are light golden brown.
• Remove the cookies from the oven and let them cool on the baking sheet for about 5 minutes, then transfer to a wire rack to cool completely.