To make the mushroom soup:

1. Melt 2 TB of the butter in a large, heavy bottomed Dutch oven or pot over medium high heat. The butter will sizzle and froth in the pot, wait to add the mushrooms until the foaming stops and the butter begins to smell nutty.
2. Add the chopped mushrooms and sprinkle with 1 tsp of the salt and the 1/4 tsp pepper. Stir to toss the mushrooms in the butter, salt and pepper until coated.
3. Allow the mushrooms to cook and release all of their liquid, about 20-25 minutes. As the mushrooms give up their liquid, they’ll stick to the pan more easily, so be sure to stir more frequently towards the end of the cooking time.
4. Once the mushrooms have started to sizzle, add the chopped onion and cook for another 3 minutes. Add the garlic and cook, stirring constantly, for another minute.
5. Add the remaining 2 TB of butter and stir until melted in. Sprinkle in the flour and stir constantly for one minute.
6. Pour in the marsala wine and stir well, scraping up the browned bits on the bottom of the pan. Add the broth and bring the soup to a simmer.
7. Stir in the parmesan and thyme. Simmer the mushroom soup for 30 minutes, stirring occasionally and scraping the bottom of the pan.
8. After 30 minutes, make a slurry from the cornstarch and water. Stream the slurry into the soup as you stir. It should thicken up right away. Once the soup has thickened, remove from the heat.
9. Stir in the evaporated milk and season with the remaining tsp of salt and a bit more pepper, if desired. Set the finished soup aside while you prepare the green beans and shallots.

To prepare the green beans:

1. Add the water to a large Dutch oven or stock pot and stir in the salt. Bring the salted water to a rolling boil, and add the green beans.
2. Boil for 5 minutes until tender crisp, and strain out the water. Add the beans to a large mixing bowl and set aside while you fry the shallots.

To fry the shallots and assemble the casserole:

1. Preheat the oven to 350 degrees. Add the 2 cups of oil to a large skillet and heat over medium high. Add one piece of shallot to test the temperature of the oil. If the shallot sizzles right away, the oil is ready.
2. Add all of the shallots to the oil and fry for 25-30 minutes, or until light golden brown. Skim the fried shallots out of the oil and add them to a paper towel lined baking sheet. They will continue to cook a bit after being removed from the oil, so skim them when they’re a shade lighter than what you want them to be.
3. Use another sheet of paper towel to gently blot extra oil from the shallots, and season generously with salt.
4. Strain the oil through a fine mesh sieve and into a clean container. Allow to cool, and store at room temperature for up to 3 months.
5. Add the mushroom soup to the bowl of green beans, along with 1 cup of fried shallots. Use a spatula to gently fold everything together until well coated and combined. Add the green bean mixture to a 2 1/2 quart baking dish and bake for 15 minutes until hot and bubbly.
6. Remove from the oven and top with the remaining fried shallots. Allow to cool slightly before serving.
7. Refrigerate any leftovers for up to a week.