Preheat the oven to 350°F. Line 2 cookie sheets with parchment paper.
Using beaters or the paddle attachment on medium speed, cream the butter and sugars until light and fluffy, about 2 minutes.
Add the egg, egg yolk, and vanilla. Beat on medium speed until combined, about 30 seconds. Scraping down the bowl as needed.
Whisk together the flour, cocoa powder, baking soda, salt, cornstarch, and espresso powder until combined.
Add it to the mixing bowl in 2 batches, mixing after each.
Mix on medium speed until combined and a dough forms. Scrape down the bowl as needed. Fold in the chopped Oreos and white chocolate.
Scoop the cookie dough. You can make large or regular size cookies- for the large I used a large cookie scoop (77 gram balls) or you can a use a medium cookie scoop ( 60 gram balls)
Portion out the cookies onto two cookie sheets. Bake one sheet a time. Position it on the center rack of the oven to ensure even baking, avoiding placement too close to the top or bottom. For the large cookies bake for 14-15 minutes or until the edges look set and the center still looks underdone, they will continue baking on the baking sheet. For regular size bake for 11-12 minutes. Do not over bake!
While the cookies are still hot, scoot them to create perfectly round thick cookies. Place a bowl or round cookie cutter that’s larger than the cookie over the cookie (the bowl should be touching the baking sheet) and push the sides up while scooting in a circular motion while hot.