Clean the mushrooms carefully removing the stems and leaving a hollow. Save a few of the stems and finely chop them for the stuffing mixture. With a grapefruit spoon you can make a deeper hollow in the mushroom, trying not to break the mushroom.
In a bowl, mix together all of the ingredients listed above thoroughly. Place the mushrooms in a buttered and oiled (approximately one tablespoon of each) baking dish or cast-iron skillet and begin stuffing until all the stuffing is gone.
Pre-heated oven to 375 degrees F. Place the mushrooms in oven and cook for 20 to 25 minutes or until stuffing is a dark golden brown.