Preheat the oven to 350°F. Line your baking sheets with parchment paper or silicone baking mats.

In a small bowl, whisk together the flour, cornstarch, baking powder, baking soda, and salt. Set aside.

In a large mixing bowl, beat the softened butter and granulated sugar until combined.

Add in the egg and vanilla extract, mixing until smooth. Scrape down the sides of the bowl.

Reduce the mixer speed to low and add the dry ingredients to the wet ingredients until a dough forms.

Fold in the chopped Oreos and white chocolate chips until evenly mixed.

Use a small cookie scoop (about 2 tablespoons of dough) to scoop out the cookies, roll them in your hand, and give them a gentle press.

Bake for 8-10 minutes or until the edges are set, letting them cool for a few minutes before transferring to a cooling rack.