Make the brownies, but spread the batter in a 9 x 13 pan so that they are a thin layer. Cook them for only 12- 15 minutes, you want them a tad on the soft side. Then allow to cool completely, you don't want them warm at all.
To make the caramel, put all the ingredients in a bowl and whip quickly with a fork until everything is smooth.
Once the brownies are completely cool, build the layers as follows.
Layer 1: brownies (just keep them in the pan you baked and cooled them in)
Layer 2: spread one of the whipped topping containers over the brownies
Layer 3: drizzle about half of the caramel over the whipped topping
Layer 4: place the peanut butter sandwich cookies on next, spreading them out evenly
Layer 5: crumble the peanut butter cups over the peanut butter cookies
Layer 6: spread the second whipped topping container over the top
Layer 7: drizzle the rest of the caramel on top and sprinkle with chocolate chips
Place in the fridge to settle over night or for at least 4-6 hours. This will help soften the sandwich cookies.
Devour. Drooling may occur.
This is best made the night before to allow it to chill and settle.
You can also make the brownies the day before that or the morning of so that they cool completely.
Just a heads up, some of the brands I use do not have dairy in their list of ingredients but do share equipment that uses dairy. I have no issue with this but if you do you should find brands for each ingredient that are made in a 100% dairy free facility.