Preheat your oven to 350°F (175°C) and line your baking sheets with parchment paper.

In a mixing bowl, whisk together the all-purpose flour, cornstarch, baking powder, baking soda, and salt.

In a large mixing bowl, beat together the softened unsalted butter and granulated sugar until fluffy, about 2-3 minutes.

Add the room temperature egg and vanilla extract to the butter and sugar mixture, mixing until smooth.

Gradually add the dry ingredients to the wet mixture and stir until a dough forms, being careful not to overmix.

Gently fold in the chopped Oreo cookies and white chocolate chips.

Using a cookie scoop, form balls of dough on the prepared baking sheet and bake for 8-10 minutes.

Allow the cookies to cool on the baking sheet for a few minutes, then transfer to a wire rack to cool completely.