Grease a 9x13 or 8x11 baking dish with natural cooking spray or oil. The 8x11 dish will yield thicker rice krispies. Set aside.

In a saucepan, melt the butter over medium-low heat. Once the butter is melted, add the marshmallows. Stir constantly to prevent the marshmallows from burning. Keep stirring until the marshmallows are almost completely melted. It's ok if you still see a few puffy peaks in there. Remove from heat and mix in the pumpkin spice.

Let the melted marshmallows cool to room temperature for 20 minutes. The cereal turns soggy quickly when you mix it with hot substances (no fun). When you let the marshmallows cool off, the rice krispies treats can stay crispy for a longer period.

While the marshmallow mixture is cooling, take the Oreos, and slice it in half with a knife. Scrape off the cream. Eat it, toss it, do whatever you want with the extra cream. Place all the cookies in a large sealable plastic bag. Crush the cookies by hitting them with a pot, a meat pounder, or anything else you can find in the kitchen. Let out your day's stress.

Mix the crushed Oreos with the rice krispies in a large bowl. Empty the marshmallow mixture into the bowl, and combine everything together. I found it easiest to use two wooden spoons for this step.

Pour the mixture into the prepared baking dish. Cut a piece of parchment paper about the size of the baking dish, and use it to help you pack the mixture into a solid block. You can also use a greased spatula. Add sprinkles on top if you like.

Let the rice krispies set for another 30 minutes and cut them into squares.

Store them in an airtight container in room temperature for a few days. Enjoy!