ha ha no this will not work, instead when taking the marsh mellows out of the pan roll it off, when rolling it off dust the joint inbetween the marshmallow and pan with flour and this should help it come off cleaner
Just melt the butter in a pot or a bowl over simmering water, add the MM and stir until liquid, add the cereal, mix in and the press into your grease baking pan and let set, I would not use a pan to do thing, do you not have a pot big enough to mix the whole batch in.