Spray a 13 x 9” rectangular baking pan with nonstick cooking spray. Line the length of the pan with parchment paper that hangs about 1 inch over the sides. Respray the bottom and sides of the pan.
In the bowl of an electric mixer using the paddle attachment, cream the butter, both sugars and vanilla on medium speed until light.
Add the egg and beat until well blended.
In a medium mixing bowl, whisk together the flour, salt and baking soda.
On low speed, add the dry ingredients. Blend well.
Remove the bowl from the motor and using a rubber spatula fold in the 1 cup chocolate chips.
Using a small offset spatula spread the batter evenly over the bottom of the prepared pan.
Make the Brownie Layer:
In the bowl of an electric mixer using the paddle attachment, blend together sugar, oil, melted butter, eggs and vanilla on medium speed until well combined.
In a medium mixing bowl, whisk together flour, cocoa, baking powder and salt until well blended.
On low speed, add the dry ingredients into the sugar and egg mixture. Blend well.
Remove the mixing bowl from the motor and using a rubber spatula fold in the ¾ cup chocolate chips.
Dollop the brownie batter over the chocolate chip batter and spread it out evenly using an offset spatula. Try not to mix the two batters.
Bake for 24-28 minutes or until the top of the brownie looks slightly crackled.
Remove from the oven and allow the cookie to cool for about 10 minutes.
While the cookie is cooling, make the ganache.
Make the Ganache:
In a medium saucepan, heat cream and corn syrup to a boil. Remove from heat and add chocolate chips, whisking until chocolate is completely melted. Allow to cool slightly.
Assembly:
Gently pour warm ganache evenly over baked cookie spreading it with a small offset spatula. Sprinkle lightly with sea salt. Allow to cool completely.