The original recipe didn't have a list of ingredients, so I kind of made one up based on the recipe.

No.1
Break stems from caps.
Sauté caps lightly in butter.
Chop stems with approximately 1/4 equal quantity of onion. (See ingredients for exact mathematical formula,)
Sauté chopped stems and onion in butter.
Fill mushroom caps with stem and onion mixture.
Grate Monterey Jack, or other cheese of choice on top.
Heat in oven or under broiler.

No.2
Same as above, but use Parmesan cheese and dot top with a pat of butter. It's also okay if you use the cheese above and dot IT with butter