Prep the dry ingredients:

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

Break up the Oreos:

Roughly break the Oreos into small and medium-sized pieces using your hands or by gently pulsing them in a food processor (just a few times—don’t turn them into crumbs!).

Cream the butter and sugars:

In a large mixing bowl, beat the softened butter, brown sugar, and granulated sugar on high speed for 3–4 minutes, until light and fluffy. Scrape down the bowl as needed.

Add wet ingredients:

Mix in the vanilla, egg, and egg yolk until fully combined and smooth.

Mix in the dry ingredients:

Gradually add the flour mixture to the butter mixture, mixing just until combined.

Fold in the chocolate chips and Oreos:

Stir in the semi-sweet chocolate chips and Oreo pieces until evenly distributed. Chill the dough for 40 minutes.

Preheat and prep:

Preheat your oven to 350°F and line two cookie sheets with parchment paper. Scoop large (3 oz) balls of cookie dough. Place 6 dough balls on one baking sheet and pop that tray in the freezer while the oven finishes preheating. Keep the rest in the fridge.

Bake:

Bake the first batch of cookies for 13–15 minutes, or until the edges are golden and the centers are still soft. Let them rest on the baking sheet for 4 minutes.

Shape & top:

Use a biscuit cutter or the rim of a glass to gently swirl around each cookie to make them perfectly round. Top with extra Oreo pieces and a few extra chocolate chips while warm.

Cool:

Transfer to a wire rack and cool until just warm or completely cooled — either way, they’re amazing!