Preheat the oven to 180C/350F/Gas 4, and line a baking tray with parchment paper, or a silicone mat. Set aside.
Whisk together the flour, baking powder, baking soda, cornflour, and salt. Set aside.
Whisk together the butter and sugars until combined. Add the egg and vanilla, and mix until combined.
Add the dry ingredients and the crushed Oreos, and mix until just combined. Fold in the chocolate chips.
Roll the dough into 1oz balls. Place a whole Oreo on top of a dough ball, then top with another dough ball, and mould the two together - sealing in the Oreo.
Repeat with all of the dough balls and Oreos.
Place onto the prepared baking tray, and bake for 12 - 14 minutes. Limit the baking tray to only 2 - 3 dough balls at a time, as they are quite large cookies.
Allow to cool on the baking tray for 10 minutes before transferring to a wire rack to cool completely.
Video
Notes
Cookies stay fresh, kept in an airtight container, at room temperature for up to 1 week. Cookie dough balls can be kept in the fridge for up to 5 days, or frozen for up to 3 months. Bake from frozen.Recipe inspired by Picky Palate