There are pareve microwave popcorns available, I get them at Fresh
Fields  ( a division of Whole Foods I think) and at the kosher market
where I usually shop.  The kosher one is a nutritional nightmare
(cottonseed oil and hydrogenated fats) but the one at the natural foods
store looks better.  it is expensive, about $1 per bag but it is helpful
to have them at my kids' friends homes and in their schools so that we
are ok if popcorn is a desired snack.  At home we just make our own of
course  (such a novelty to their friends sadly).  Check at your closest
natural foods store.

I dont' think it has a butter flavor though.

Larissa Blechman