a gratin dish or similar baking dish (mine is 8x12) with at least a 2 quart capacity
3large shallots, peeled and very thinly sliced into rings
vegetable oil for frying
1 1/2lbsgreen beans, trimmed
2cupshalf and half, or cream
1/2ouncedried mushrooms (I used Shitake)
1heaped cupshredded Gruyere cheese, divided
salt and fresh cracked black pepper to taste
dash of fresh grated nutmeg, or more to taste
Note: you can fry the shallots first, or while the casserole is cooking. Fill a saucepan with 2 inches of oil and heat on medium high until hot, or a clip on thermometer reads 325F
Mix the flour and salt together, then gently toss the shallots in the flour, carefully separating the rings as you add them.
Fry the shallots, in batches, until golden, it should take under 2 minutes if your oil is hot enough. Drain on paper towels. Note: remove any brown bits from the oil in between batches, so they don't burn.
Heat the cream to a simmer, then remove from the heat and add the dried mushrooms, stirring well. Cover and let sit for 30 minutes.
Preheat the oven to 350F
Trim the beans but leave them whole. Blanche them in a large pot of boiling water for a total of about 3 minutes, just to take the raw edge off, they will still be crunchy.
Prepare an ice bath in a large bowl. Drain the beans and immediately plunge them into the ice water to stop the cooking and set their bright color. Add more ice if necessary to keep the water cold, then drain the beans on a clean towel.
Puree the mushrooms and cream in a food processor or high speed blender until smooth. You may still have some texture to your sauce, that's ok, just get it as smooth as you can.
Melt butter in a medium pan and add the flour to make a roux. Stir constantly for about 2 minutes over medium heat, but don't let it take on color.
Add the sherry to the pan and stir or whisk well until blended, let the mixture cook for a minute, stirring or whisking constantly. Then add the mushroom sauce and whisk until the mixture comes to a simmer and is smooth and thickened. Remove from heat and stir in 1/2 cup of the cheese. Season with salt and pepper to taste. Start with 1/2 teaspoon of salt, but you will likely need more. Add a dash of nutmeg to taste. (Don't skip this step, the flavor is so wonderful.)
Layer half your beans into your casserole, then drizzle half the sauce over the beans, nudging the sauce down and around all the beans. Repeat with the remaining beans and sauce. Try to get the sauce evenly distributed.
Sprinkle the top with the remaining cheese and bake for 35-45 minutes, until golden and bubbly. Note: tent the casserole loosely with foil about halfway through if it browns too much. Top with the fried shallots and serve immediately.
Variations:You can use whole milk in place of half and half or cream, but the sauce will not be as rich and creamy.Add 3/4 ounce dried mushrooms for more pronounced mushroom flavor.Use up to 1 cup cheese on top of the casserole if you like things cheesier.You can substitute canned fried onions for the fried shallots.
https://theviewfromgreatisland.com/favorite-green-bean-casserole-from-scratch-recipe/ November 4, 2019