In a small bowl, whisk together all purpose flour, baking soda, salt, and cornstarch.
In a mixing bowl, add the room temperature butter, brown sugar, and white sugar. Beat for about a minute or two until light and fluffy using a hand mixer or stand mixer fitted with a paddle attachment.
Add the egg, egg yolk, and vanilla extract. Beat again until smooth. Scrape the sides of the bowl as necessary.
Add the dry ingredients to the wet and combine until a dough forms.
Mix in the Oreos, semi sweet chocolate chips, and white chocolate chips. Then let the dough rest at room temperature for 20 minutes.
Preheat oven to 350°F.
Line a sheet pan with parchment paper.
Scoop out portions of the dough about the size of ¼ to ⅓ measuring cup. Make sure to space them apart, 6 cookies per sheet. You can use a large ice cream scoop to portion it.
Pop in the oven to bake for about 11 to 12 minutes until the edges are golden and the center is still a bit soft. The cookies will continue baking out of the oven on the hot pan.
Leave them on the pan for about 10 minutes or until firm before transferring them to a cooling rack to finish cooling and enjoy!
