This green bean casserole is a classic dish that is perfect for holiday gatherings or weeknight dinners. Fresh green beans are blanched until tender and then mixed with a creamy sauce made from mushrooms, onions, and milk. The mixture is then topped with a layer of crispy fried onions and baked until golden and bubbly. The combination of the tender green beans, creamy sauce, and crispy onions creates a flavorful and satisfying casserole that is sure to be a hit with the whole family. Serve it as a side dish alongside roasted turkey or chicken for a complete and festive meal.