Recipe: Vegetarian Mushroom Bisque (like Panera's) - Thanks to Deborah's description I think the following recipe

Thanks to Deborah's description I think the following recipe is close to what you are looking for. You will just have to add the brie and Swiss cheese mentioned by Deborah.

MUSHROOM BISQUE
Source: Molly Katzen's New Moosewood Cookbook
Yield 8 servings

A lovely, creamy vegetarian/vegan soup which is the essence of mushrooms.

2 potatoes, peeled and diced
1 1/2 cups water
1 1/2 tbsp butter or olive oil
2 cups onion, chopped
1 stalk celery, minced
1 1/2 pounds mushrooms
1 1/2 tsp salt
2 cloves garlic, minced
1/4 tsp thyme
3 tbsp dry sherry
2 tsp soy sauce
black pepper
1 cup milk or soy milk
TO SERVE:
1 batch croutons
scallions or chives, minced

Boil the potatoes and water in the small sauce pan until tender, about 10 minutes.

Puree potatoes with remaining cooking water.

Heat butter in large pan over medium heat, saute onions and celery for five minutes.

Add mushrooms, salt, garlic, and thyme, cover, and simmer, stirring occasionally, for 10 minutes.

Turn off heat and add sherry, soy sauce, and pepper. Puree with milk.

Combine potato and mushroom purees and heat until very hot. (Now you can add the cheese)

Top with croutons and scallions and serve.