Seriously, every time I make this everyone LOVES it. And it cleans out my pantry. It's sort of rice krispie treats on steroids. All amounts are approximate.
I use a 4.5qt dutch oven
Melt about 1/2 stick of butter over medium heat
Add about 1 1/2 bags mini marshmallows, stirring constantly until melted
Add a BIGASS scoop of peanut butter and stir till melted
Keeping heat on, add whatever cereal you have in the house until the pot is nearly full (Cheerios - regular or honey nut, Reeses, Rice Krispies, Rice Chex, Corn flakes all work well - mix and match. Cereals that are too sweet -Capn Crunch for example - will make the gunk too sweet)
Stir to coat - this works pretty easily if you keep the heat on
Dump the gunk into a buttered casserole dish. Do not press down. Heat the pan to release any stuck bits.
Serve with a spoon and eat like uncivilized beasts... with your hands.