How to do it…

1. Line a 9x9 pan with enough parchment paper to overhang for easy removal. Coat with cooking spray. Or just coat with cooking spray, I don't bother with parchment because it'll lift out on it's own. But if you're being fancy or making this for company, perhaps you should do the whole shebang.
2. In a large pan (nonstick if possible, but don't worry - this gooey, sugary mess will clean up relatively easily if you don't), melt butter over low heat. Once melted, add all but 2.5 cups of the marshmallows. Stir until melted, and don't leave this alone. You'll wanna stay on top of it. Once melted, remove from heat and stir in the salt and vanilla. And don't dis the salt! Seriously, it adds a little extra something, especially with all of this sweetness!
3. Gently stir in all the cereal and the remaining marshmallows. Now, a note here, you can nix the Rice Krispies and go all in with Fruity Pebbles, but the Krispies cut the sugar-shock factor. Seriously, they make these better.
4. Pour into pan and press carefully to compact. Another note, I don't press. I like the lumpy mess. Mostly because I circumvent the next instruction and just rip some off and eat it still warm. But if you want order...do the press thing.
5. After cooled, cut into bars. The recipe I found for this says "best served same day" which I think is utterly hilarious. Like, this would not last a whole day...ever. Enjoy!