Preheat the oven to 350 degrees F. Grease a 2-quart baking dish with the butter and set aside.
In a large bowl, combine the green beans, Wild Mushroom Soup, 2 teaspoons of Essence, and 1 1/2 cups of the cheese, and stir well. Pour into the prepared dish, sprinkle the remaining 1/2 cup of cheese on top, and bake until bubbly, 30 to 35 minutes.
In a large saucepan, add enough oil to come about 3 inches up the sides of the pan, and heat to 360 degrees F.
Pat the onions dry. Drizzle hot sauce on the onions and toss. In a bowl, combine the flour and 2 tablespoons of the Essence. Add the onions and toss to coat evenly. Shake the onions to remove any excess flour and add in batches to the hot oil. Cook, stirring occasionally, until crisp and golden brown, 1 1/2 to 2 minutes. Remove with a slotted spoon and drain on paper towels.
Top casserole with fried onions and serve.
In a large pot, melt the butter over medium-high heat. Add the onions, celery, and cayenne and cook, stirring, until soft, about 4 minutes. Add the garlic and cook for 30 seconds. Add the mushrooms, thyme, salt, and pepper, and cook, stirring until the mushrooms give off their liquid and start to brown, about 7 minutes. Off the heat, add the brandy. Return to heat and bring to a boil and cook until glazed, about 2 minutes. Add the stock and return to a boil. Reduce the heat to medium-low and simmer uncovered, stirring occasionally, for 15 minutes.
Remove from the heat and puree with a hand-held immersion blender, or in batches in a food processor. Add the cream, return to a simmer, and cook for 5 minutes. Remove from the heat and adjust seasoning, to taste.
Combine all ingredients thoroughly.
Recipe from New New Orleans Cooking by Emeril Lagasse and Jessie Tirsch, Published by William Morrow, 1993.