Freezing the Brie firms it, so removing the rind and slicing the cheese are much easier.

Ingredients
1/4 cup (1/2 stick) butter
3 large leeks (white and pale green parts only), thinly sliced (about 3 cups)
8 ounces shiitake mushrooms, stemmed, sliced
8 ounces crimini mushrooms, sliced
2 tablespoons all purpose flour
4 cups chicken stock or canned low-salt chicken broth
1 cup whipping cream
2 tablespoons dry Sherry
4 green onions, sliced
12 1/4-inch-thick slices French-bread baguette
1/2 pound Brie, frozen, rind removed, cheese cut into 1/4-inch-thick slices
2 tablespoons chopped fresh chives

Directions
Melt butter in large pot over medium-high heat. Add leeks and all mushrooms; sauté 8 minutes. Add flour and stir 1 minute. Gradually mix in stock. Bring to boil, stirring frequently. Reduce heat and simmer 10 minutes. Add cream and Sherry and simmer 5 minutes. Season to taste with salt and pepper. Stir in green onions. (Soup can be made 1 day ahead. Cool slightly. Refrigerate uncovered until cold, then cover and refrigerate.)

Preheat oven to 350*F. Place bread slices on baking sheet. Bake until light golden, about 10 minutes. Cool. Top croutons with cheese slices.

Preheat broiler. Place 6 ovenproof bowls or soufflé dishes on baking sheet. Bring soup to simmer; ladle into bowls. Top each with 2 croutons. Broil until cheese is completely melted, about 2 minutes. Sprinkle with chives and serve. Makes 6 (first-course) servings.

Source:  Bon Appétit