In a large mixing bowl, whisk together your butter, sugar, and brown sugar. Beat for about a minute or two until light and fluffy using a electric mixer.
Add in your egg, egg yolk, and vanilla extract. Whisk until smooth.
In another bowl, whisk together all purpose flour, baking soda, salt, and cornstarch. Add to your butter and sugar mixture, whisk until combined.
Mix in your white chocolate chips and oreos.
Preheat oven to 350°F. Line a large baking sheet with parchment paper, set aside.
Allow your dough rest at room temperature for 20 minutes.
Using a large cookie scoop, place your cookie dough on your prepared baking sheet at least 2 inches apart.
Bake for 11 minutes or 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.
Allow to cool on your baking sheet for at least 10 minutes before transferring to a cooling rack, enjoy!
