Brownie Layer

1. Preheat your oven to 350F/180C.
2. 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.
3. Take off of the heat, let sit for 5 minutes then add the egg and whisk to combine.
4. Add the baking powder, 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. Set aside while you prepare the cookie layer. 

Cookie Layer 

1. In a 10-11-inch skillet add the butter and cook over low heat to melt the butter. Remove from the heat and mix in the sugars, let cool for 5-10 minutes. Add the egg and vanilla and mix until fully combined.
2. Add the flour, baking soda, baking powder, and salt and gently fold in. Mix in the chocolate chips. Then form 5-6 little hole areas for the brownie batter to sit on top. Use a cookie scoop to add the brownie batter. Then sprinkle more chocolate chips on top if desired. Bake for 23-26 minutes, don't overbake the brookie. You want a toothpick in the center to come out with moist crumbs, not completely dry. Let the brookie cool for 5-10 minutes before digging in. Be careful as the pan will be out.