Start by bringing a large pot of water to a rolling boil. Add the trimmed and halved green beans, cooking them for about 5 minutes until they turn bright green and are just tender. Once cooked, quickly plunge them into an ice bath to stop the cooking process and retain their vibrant color.

Preheat your oven to 425°F (220°C). In a mixing bowl, toss the wild mushrooms with extra virgin olive oil, fresh thyme, salt, and pepper until well-coated. Spread them evenly on a baking sheet and roast for about 20 minutes or until they are golden brown and fragrant, stirring halfway through for even cooking.

In a medium saucepan over medium heat, melt the unsalted butter. Once melted, sauté the minced garlic and shallot for 2–3 minutes until soft and aromatic. Stir in the all-purpose flour, cooking for another minute to create a roux. Gradually pour in the whole milk, whisking constantly until the mixture thickens into a creamy béchamel. Season with nutmeg, soy sauce, lemon zest, lemon juice, and Parmesan cheese, stirring until smooth.

In a large mixing bowl, gently fold together the blanched green beans, roasted mushrooms, and the rich béchamel sauce until the beans are completely coated. Be careful not to break the beans. Pour this delicious mixture into a greased 9x13-inch baking dish, spreading it evenly for even baking.

Set your oven to 375°F (190°C) and bake the assembled green bean casserole for 20 minutes. Look for bubbling edges and a lightly golden top, which signals that the casserole is nearly done and the flavors have melded beautifully.

While the casserole bakes, heat canola oil in a deep frying pan over medium-high heat. Add the thinly sliced shallots, frying them in batches for about 2-3 minutes until they are golden and crispy. Remove them from the oil using a slotted spoon, draining on paper towels, and season with a pinch of salt.

After the initial bake, remove the casserole from the oven and sprinkle the crispy shallots generously over the top. Return the casserole to the oven for an additional 5 minutes. This will allow the shallots to crisp further and add an irresistible crunch to your Upscaled Green Bean Casserole.