I bought this yesterday https://www.perfectbrownie.com/
and tried it out today.
I sprayed the heck out of it with cooking spray to make sure that my brownies would come out of the pan nicely.
I have to say that it was difficult getting my brownies out of this pan. I even put them in the refrigerator for a couple of hours to make sure that they were very cool.
I think that you need to flour and spray this divider thing.
But I did get nice square shaped brownies.
Be sure to use a cookie sheet when you bake with this brownie pan, because some of the batter did leak out of the bottom of the pan.