I just saw Nigella make this on one of her TV shows and I had to post it. It is utterly yummy. You can experiment with toppings to create your own flavor sensations.
- Put your cleaned mushroom caps, bottom side facing up, in a small baking dish.
- In a bowl, mash the butter and mix in the garlic, parsley, and salt and pepper to taste.
- Put about 2 tbls. of butter mix on top of each mushroom.
- Bake mushrooms until tender (15-20 min.).
- Slice foccacia down the center horizontally to create a bun.
- Dip the inside of each bun half in the oozing hot butter liquid in the mushroom baking dish to moisten.
- Put a mushroom in the center and top with lettuce, sliced onion, and salt and pepper to taste.
- As you eat, the butter and mushroom juices will drip out of your sandwich, so be prepared.