Mix Dry Ingredients: In a medium bowl, whisk together the all-purpose flour (1 1/2 cups), bread flour (3/4 cup), cornstarch (1 1/2 teaspoons), baking soda (1 teaspoon), and kosher salt (1 1/2 teaspoons). Set aside.
Brown the Butter with Milk Powder: In a medium, light-colored saucepan, melt the butter (1 cup) over medium heat. Once melted, sprinkle in the powdered milk (2 tablespoons) and stir constantly with a heatproof spatula, breaking up any clumps. Continue cooking, stirring constantly, scraping the bottom and sides often, until the mixture foams and the milk solids turn a deep amber, pecan-brown color and smell nutty (about 5–7 minutes).Immediately remove from the heat to prevent burning and pour the browned butter into a large heatproof bowl, scraping in all the toasted bits — they add rich flavor.
Add Sugars and Cool: Add the brown sugar (1 cup) and granulated sugar (1/2 cup) to the hot browned butter and stir until smooth and glossy. Let the mixture cool for about 5–10 minutes, or until it’s warm but not hot to the touch (around 95°F). This step prevents the eggs from cooking when added.
Add Wet Ingredients: Whisk in the corn syrup (2 teaspoons), eggs (2), egg yolks (2), and vanilla (2 teaspoons). Mix vigorously by hand until fully combined and slightly thickened — the mixture should look glossy and cohesive.
Combine Dry and Wet Mixtures: Add the flour mixture to the butter mixture all at once, along with both types of chocolate chips (3/4 cup Guittard + 1/3 cup semi-sweet) and the 18 chunked Oreos. Fold gently with a spatula until no dry streaks remain. Stop mixing as soon as the dough comes together to keep the cookies tender.
Portion and Chill: Scoop the dough using a #40 cookie scoop (about 40–41 g) for standard cookies or a #24 scoop (71–72 g) for bakery-sized cookies. Roll each portion into a smooth ball. Cover and chill the dough for at least 2 hours (to solidify the butter) or up to 48 hours for deeper flavor and thicker cookies.
Bake: Preheat the oven to 370°F (188°C) and line baking sheets with parchment paper or silicone mats. Arrange dough balls 2–3 inches apart (6–8 per sheet).Bake smaller cookies for8–9 minutes.Bake larger cookies for 10–11 minutes.The edges should be lightly golden while the centers remain soft and domed.When done, the edges should be lightly golden, but the cookie tops will still be domed and gooey.
Finish: Remove cookies from the oven and immediately use a round cookie cutter or spatula to nudge them into perfectly circular shapes, if desired. Gently press additional Oreo chunks onto the tops while the cookies are hot. Sprinkle with flake salt if using.
Cool: Let cookies cool completely on the baking sheet. They’ll continue to bake slightly as they rest, setting the centers and creating the perfect chewy texture.
Notes
Bake one test cookie first. Every oven runs a little different! You’ll know if you need another minute or two.
Round cookies while warm. Use a circular cutter to gently swirl each cookie into a perfect round right after baking.
Avoid overbaking. The centers should look slightly underdone — they’ll finish cooking as they cool.
For taller cookies, chill overnight or even 24 hours. Slow hydration = thick, chewy perfection.