In a bowl, whisk together the flour, cornstarch, baking powder, baking soda, and salt. Set aside.
In a large mixing bowl, cream together the butter and sugars until light and fluffy.
Add in the vanilla and eggs, and mix to distribute.
Add the dry ingredients to the bowl of egg mixture and mix until well combined. You may need to use your hands to help mix it in. The dough will be thick.
Fold in the chocolate chips and crushed oreo.
Scoop the dough into 2 tablespoon sized scoops and place on a parchment lined baking sheet at least 2 or 3 inches apart.
Place one mini oreo into the center of each dough ball.
Bake the cookies for 10 minutes until the edges look set.
Let rest on the baking sheet for 2 minutes before transferring to the cooling rack.
Continue until all cookies have been cooked and cooled.
Notes
Recipe Tips:
Allow cookies to sit on baking sheet for AT LEAST 2 minutes (preferably longer) after coming out of the oven to finish cooking and set, preventing them from falling apart when transferring to cooling rack.
Making in Advance:
Chill dough in freezer for a short time or fridge for longer, adjusting based on desired quantity of cookies.
Consider balling out all dough on one baking sheet and chilling in fridge or freezer while baking another sheet.