Brown the butter: Melt the butter in a light-colored skillet over medium heat, swirling gently until it foams and the edges take on a toasty amber color with a fragrant nutty aroma. This should take about 3–5 minutes. Remove from heat and cool to room temperature before using.

Whisk dry ingredients: In a medium bowl, whisk together the flour, baking soda, baking powder, salt, and cornstarch (if using). Set aside.

Mix the wet with the sugars: In a large bowl, whisk the cooled brown butter with the granulated sugar and brown sugar until the mixture is glossy and smooth. This usually takes about 1–2 minutes with a sturdy whisk or a hand mixer on low.

Incorporate eggs and vanilla: Beat in the eggs one at a time, then add the vanilla. The batter should look thick and almost shiny.

Combine by adding dry ingredients: Add the dry ingredients in two additions, mixing just until no dry streaks remain. Overmixing can make the cookies tough.

Stir in chocolate: Fold in the chocolate chunks until evenly distributed. Think big chocolate pockets in every bite.

Chill the dough: Cover and refrigerate for 30–60 minutes (or up to 2 days). Chilled dough spreads less, giving you thicker, more tender cookies.

Bake and finish: Preheat your oven to 350°F (175°C). Line baking sheets with parchment. Scoop dough (about 2 tablespoons per cookie) and place 2 inches apart. Bake 10–12 minutes, until the edges are golden and the centers look just set but still soft. Remove from oven and let cookies rest on the sheet for 5 minutes before transferring to a rack. A light sprinkle of flaky salt on hot cookies is a wonderful finish if you like.