Preheat oven to 375°F

Whisk together flour, cornstarch, cocoa powder, baking soda, and salt in a medium bowl.

In the bowl of a stand mixer, beat butter, granulated sugar, brown sugar, and vanilla until creamy.

Add eggs one at a time, beating well after each addition.

Gradually beat in the flour/cocoa mixture on low speed until thoroughly combined.

Carefully stir in the chopped Oreos Pieces and chocolate chips.

Place in the refrigerator for at least an hour. The more chill time, the deeper the flavor will be.

Using a large cookie scoop, place cookie dough balls onto ungreased cookie sheets (or use parchment paper).

Bake for 12 minutes and remove from the center when it isn't fully baked - they will continue baking on the pan.

Allow to cool at room temperature on the baking sheet for 15 minutes before moving to a wire rack.