Preheat oven to 350F and lightly spray a 9 x 13-inch baking pan with cooking spray.
In the bowl of a stand mixer fitted with a paddle, cream together butter and sugar.
Add 4 eggs, 1 1/2 tsp. vanilla extract, salt, cocoa powder, and baking soda and mix until well combined. Pour in flour a little at a time until incorporated.
Separate dough in two and press one half into the prepared pan. Bake the dough that is in the pan for 10 minutes, set aside the other half.
To prepare cream cheese filling, in the bowl of a stand mixer, beat cream cheese until light and smooth. Pour in sugar and beat until creamed. Add egg, vanilla extract, and sour cream and mix again.
Layer Oreos on top of cooked brownie layer and pour cheesecake filling over the Oreos.
Crumble dough over top of the cheesecake filling and bake again for 22-25 minutes. Let cool for 1 hour, and chill for at least 3-4 hours before slicing and serving.