Don’t let the number of ingredients discourage you from making this outstanding appetizer. It’s sure to be a hit at any dinner or cocktail party. –Mountain Top Inn, Chittenden, Vermont
If using fresh clams, wash thoroughly to remove grit and sand. Place in a large pot, cover with water, and add lemon halves and salt. Bring to a boil and cook until shells open. Remove clams and cool under running water; reserve ½ cup of the cooking liquid.
Wash mushrooms, remove stems and reserve, and place caps on a cookie sheet; set aside.
When clams have cooled, remove the usable portion from the shell, dice finely, and set aside. Puree onion, celery, green pepper, reserved mushroom stems, bacon, and pimiento using a grinder or food processor. Saute this mixture in a skillet with butter and reserved clam broth on moderate heat until liquid is reduced. Set aside to cool.
Combine diced clams, pureed mixture, and remaining ingredients and mix by hand. If stuffing is too wet, add additional bread crumbs. Place stuffing in mushroom caps and bake at 350 degrees F for 20 minutes.