Combine the oil, water, & eggs in a large bowl. Pour in the brownie mix & combine until a smooth batter forms. Set the bowl aside.
Cheesecake Swirl
Combine the cream cheese, egg , sugar, and vanilla in a bowl. Beat on medium speed for 2-3 minutes until everything is combined.
Pour the brownie mix in a square 8x8 pan. Spread out the cheesecake mix on top & swirl both batters around with a knife. Top off the brownies with Oreos.
Bake the brownies for 30-35 minutes.
Let the brownies cool in the pan for 10-15 minutes