This is not your grandma's green bean casserole! Inspired by the casserole of my youth, but reimagined with fresh green beans, roasted wild mushrooms, creamy béchamel sauce, and a crispy shallot topping. This will become your favorite Thanksgiving side!
Bring a pot of salted water to a boil and add beans. Boil about 5 minutes or just until tender. Plunge beans into an ice bath and remove when cooled. Spread beans out on paper towels to dry.
Preheat oven to 425 degrees. Line a baking sheet with nonstick foil or parchment paper.
Spread sliced mushrooms and thyme onto the baking sheet, drizzle with olive oil, and sprinkle with salt and pepper.
Melt butter in medium saucepan over medium heat. Add minced garlic and shallots and cook for 2 minutes.
Add the flour and cook 2-3 minutes, stirring well. Pour in the milk, whisking constantly.
Bring to a boil, then reduce to a simmer. Cook for about 5 minutes or until thickened, whisking frequently.
Stir in nutmeg, soy sauce, lemon zest, lemon juice, Parmesan, salt, and pepper to taste.
Spray a 13 x 9 inch baking pan with cooking spray.
Remove from the béchamel sauce from the heat and combine beans, mushrooms, and béchamel sauce in a large bowl. Stir well and then pour into the prepared pan.
Bake (at 375 degrees) for about 20 minutes or until hot and bubbly.
Heat canola oil in a heavy pot fitted with a deep fry thermometer to 375 degrees.
Remove the shallots, gently shaking off extra flour, and add half the shallots to the heated oil.
Remove shallots from oil and allow to drain on a paper towel-lined plate. Sprinkle lightly with salt.
Top the heated casserole with crispy shallots and return to oven to bake for another 5 minutes. Watch to be sure shallots do not burn!