Because this comes together pretty quickly, measure out all your ingredients beforehand and have them ready to add.
Prep a 9x9 pan with parchment and lightly grease. Set aside.
In a large saucepan on medium low, add your butter and melt.
Add all of your marshmallows except for 1 cup, and melt the marshmallows.
When marshmallows have melted down, add vanilla and black cocoa and mix until combined.
Remove pan from heat and add in rice cereal and crushed oreos. Stir until the marshmallow mix has evenly coated all the cookies and cereal.
Transfer into your prepared pan and smooth into an even layer. Using the butter wrapper can be helpful to lightly push down.
Let your bars cool for at least an hour before cutting in, this will allow the marshmallow to firm up a little more and the bars to hold shape.
Optional - Before cutting, melt 2 ounces of white chocolate and drizzle over the top before cutting.
Store in an airtight container for up to 3 days. Enjoy!
