Whisk together the flour, corn starch, salt, and baking soda in a medium bowl and set aside.
Break the Oreos into large pieces (4-6 pieces per cookie) with your hands and set them aside.
Using a stand mixer fitted with a paddle attachment or an electric hand mixer, cream the butter and cream cheese together. Add the white and brown sugar in and beat until light and fluffy. Add the egg and vanilla in and mix until combined. Scrape the bowl down and mix one more time to combine.
Add the dry mixture into the wet and mix on low until almost combined. Add ½ cup white chocolate chips and the broken cookies, then fold into the batter until evenly distributed using a spatula. Cover and chill for at least an hour.
Preheat oven to 350F, then portion out roughly two tablespoon-sized pieces (50g), roll into balls, and place on parchment or silicone-lined baking sheets about two inches apart. Press the remaining white chocolate chips onto the tops of the cookies and bake for about 11 minutes or until the edges are set and just turning golden.
Make sure your brown sugar is soft and moist. If your brown sugar has hardened, not to worry! Simply add the sugar to a bowl, place a moist paper towel on top, and microwave it for 20 seconds. Repeat if the brown sugar is still not soft.
Do not skip chilling the cookies. As the dough is super soft, chilling will make it easier for you to roll and keep the dough from flattening in the oven.
I like using my hands to break up the Oreos as there are fewer crumbles than when I roughly chop them with my knife. Be sure to not accidentally crush them into fine-crumbles as you want chunks of Oreos in the cookies.
Be careful not to overbake the cookies. They may look underdone when you pull them out of the oven, but they’ll firm up once cooled. They should look just golden instead of golden all the way through like a chocolate chip cookie.
Make sure to line your cookie sheet with baking parchment or a silicone mat. A lined pan helps the cookies bake more evenly. If you add the dough directly onto a sheet pan, they’ll stick, and the bottoms will be more brown.
Even though it’s only 2 teaspoons, the cornstarch is essential for soft cookies, so don’t skip it.
Make sure your baking soda hasn’t expired, as it’s an essential ingredient for the shape and texture of the cookies. Without the baking soda, your cookies won’t be as soft and fluffy.