Chocolate Chip Cookie Layer

1. Preheat your oven to 350F/180C and line a 9X9 square pan with foil, making sure to let the foil overhang on the edges to help pull the brownies out later. Make sure to grease the foil heavily.
2. In a large bowl add the melted butter and sugars, mix until fully incorporated. Add in the egg and vanilla extra and whisk until fully combined.
3. Add the flour, baking soda, and salt, and gently use a spatula to fold into the wet ingredients. As there are a few flour streaks left add the chocolate chips and gently fold them into the batter.
4. Pour batter into the prepared pan and line the Oreos in one even layer on top of the cookie dough.

Brownie Layer

1. In a large pot add the water, butter, sugar, and cocoa powder. Cook on medium heat for 2-3 minutes until it is all combined together, the mixture will look weird and not liquidy enough, that is fine. Then add the oil and vanilla extract. Cook on low for an additional minute and mix to combine everything.
2. Take off of the heat, let sit for 5 minutes then add the egg and egg yolk. Whisk to combine.
3. Add the baking soda, salt, cornstarch, and mix to combine. Gently add the flour by using a spatula to fold in until just combined, just before there are no flour streaks add your chocolate chunks/ chips. Do not over mix, this will affect the end product.
4. Pour the brownie batter evenly over the Oreo layer. Bake for 35-40 minutes.
5. You want a toothpick in the center to come out with moist crumbs, not completely dry. Place the pan on a wire rack to cool completely before cutting. This is a must, let the brownies cool a minimum of 2 hours before attempting to cut. Store the brownies in an air-tight container on the counter for up to 4 days.