Pinterest Challenge: Oreo Marshmallow Cookie Bars

(Note: this should have been shared in October - but I forgot!)

Well, I know I found this idea through Pinterest, but... I can't seem to find the link today.

The basic idea is to make rice crispy treats - but with crushed Oreo cookies instead of the cereal.

The first time I attempted this I used 1 box of regular Oreo cookies, 1 10 oz bag of mini marshmallows, and half a stick of butter.

1) Crush the cookies - I used a food processor, though in theory you can put them in a bag and crush them with a rolling pin or something.
2) Melt the butter and marshmallows - I did it in the microwave (15-20 seconds then stir, repeatedly)
3) Mix the cookies into the gooey mess
4) When everything is combined, pour into a pan and let cool at least 10 minutes.

I was a little surprised when batch number one (regular Oreo cookies, 10 oz mini marshmallows) turned out to be less than a full pan's worth of cookie bar. It made about an 8x8 size bar that was a little on the thin side:

Yeah, not quite so appetizing to look at, right? But, they were pretty good. The sweetness of the marshmallow cut down the bitterness of the chocolate cookie pieces, and the other all taste was neither too sweet nor too bitter.

Since that batch turned out a little less than I'd hoped, and since we ate it all (eventually) without any other opinions, I wanted to try again. This last weekend I made a second batch - doubled. This time I went with two packages of a knock off brand, and a 20 oz bag of large marshmallows, with slightly less than a whole stick of butter. (And I still think the butter could be cut down a little more next time.) Same process, but completely different looking - and tasting - results:

I didn't have a large enough bowl for mixing, so I did end up with a less well blended cookie bar - but that made it better. Instead of every bite tasting exactly the same, there was some variation in how much cookie or marshmallow. And this 'double' size easily filled a 9x13 pan with a thick layer. I don't know if it was the change in marshmallow size or brand of cookie, or something else, but this second batch was much better all around.

Now I'm curious to see if I can make a peanut butter version. I'd like to try yet this week - but I think I need a little break from marshmallows... Don't get me wrong - these cookies are good and I could certainly eat more of them -- but I probably shouldn't eat part  most of three pans worth in two weeks!

Edit: I tried a peanut butter version. Every recipe I found said to use peanut butter and marshmallow. That didn't really work. After trying a bite, two of my taste testers said they'd never used both when making peanut butter rice crispy cookies, so now I'm wondering if I should try it again with only the peanut butter or if I call it a failure... Again, probably should let some time pass before I try again.