- 7 tablespoons unsalted butter
- 1 1/2 cups finely chopped yellow onions
- 3/4 cup finely chopped green bell peppers
- 3/4 cup finely chopped celery
- 1/2 teaspoon salt
- 1/4 teaspoon cayenne
- 2 bay leaves
- 1 teaspoon minced garlic
- 1/2 cup finely chopped green onions (green and white parts)
- 1/4 cup finely chopped fresh flat-leaf parsley
- 1/2 cup Chicken Stock or 
- canned low-sodium chicken broth
- 6 cups 1-inch cubes day-old French bread
- 1 large egg, lightly beaten
- 1 pint shucked oysters with their liquor
- 1 cup freshly grated Parmigiano-Reggiano
- 3 tablespoons fine dried bread crumbs
- 6 large egg whites
- Oyster Tasso Sauce 
- Preheat the oven to 350?F. Butter a 2-quart baking dish with 1 tablespoon of the butter, and set aside.
- Melt 5 tablespoons of the butter in a large heavy saucepan over medium-high heat. Add the onions, bell peppers, celery, salt, cayenne, and bay leaves and cook until the vegetables are soft, about 7 minutes. Add the garlic, green onions, and parsley and cook, stirring constantly, until fragrant, about 1 minute. Add the chicken stock, remove from the heat, and stir in the bread cubes. Mix in the egg, then the oysters and their liquor, and the cheese.
- Spread the mixture in the prepared pan. Bake until golden brown and bubbling on top, about 1 hour and 15 minutes.
- Let cool, then refrigerate until well chilled, at least 6 hours and up to 8 hours.
- Preheat the oven to 375?F. Butter six 1/2-cup ramekins with the remaining 1 tablespoon butter. Sprinkle the bread crumbs inside the ramekins and shake to coat evenly with the crumbs.
- Scoop the oyster dressing into a large mixing bowl with a spoon and break into 1/2- to 1-inch pieces. Remove and discard the bay leaves.
- Beat the egg whites in a large bowl with a hand mixer on high speed or a wire whisk until stiff peaks form. With a rubber spatula, gently fold the beaten whites into the dressing. Spoon into the prepared ramekins and place the ramekins on a baking sheet.
- Bake until the soufflÈs are golden brown and have risen above the edge of the ramekins, about 25 minutes. Serve immediately, with the sauce on the side. Have each guest make a hole in the center of his or her soufflÈ, and spoon in the sauce.