I have seen this (several variations) on Pinterest.
Here is my variation.
a box of brownie mix (your choice)
a package of Oreo or similar cookies (or any cookie)
Peanut-butter (about a cup)
Ingredients listed on the box of brownie mix
Follow directions on the box of brownie mix.
Before you pour the mix into your chosen dish, top oreos (one at a time) with about a teaspoon or so of peanutbutter and place cookie-side-down in single layer into the pan.
Then cover with the mix. Bake according to directions.
The cookies are so soft when the brownies are still warm. When they have cooled to room temp, the crispness comes back.