For me, it would be "a bowl & spoon". I love rice krispy treats, and if they crumble after being made, it only means I will be getting a bowl and a spoon out. 'Cause oh yeah, I'm gonna be eating them no matter what.
Actually as a tip, you can use any kind of dry cereal to make a treat like this in the same way. And just for fun, substitute about 1/4 of the amount of rice krispies with pebbles to add flavor and color.