Ingredients:

  • 1.5 lbs (680g) fresh green beans, trimmed
  • 1 tablespoon (15 ml) olive oil
  • 1/2 teaspoon (2.5 ml) salt
  • 1/4 teaspoon (1.25 ml) black pepper
  • 4 tablespoons (57g) unsalted butter
  • 8 oz (227g) cremini mushrooms, sliced
  • 1/2 teaspoon (2.5 ml) salt
  • 1/4 teaspoon (1.25 ml) black pepper
  • 1/4 cup (30g) all-purpose flour
  • 3 cups (710 ml) whole milk, warmed
  • 1/4 teaspoon (1.25 ml) freshly grated nutmeg
  • 1/4 cup (60 ml) dry sherry (optional)
  • 1/4 cup (28g) grated parmesan cheese
  • 2 large yellow onions, thinly sliced
  • 1 cup (120g) all-purpose flour
  • 1 teaspoon (5 ml) salt
  • 1/2 teaspoon (2.5 ml) black pepper
  • Vegetable oil, for frying (about 3 cups / 710 ml)

Instructions:

  1. Blanch the green beans in boiling salted water until bright green and crisp-tender. Shock in ice water to stop cooking. Drain well and set aside.
  2. Toss onion slices with flour, salt, and pepper. Fry in hot oil (around 350°F/175°C) until golden brown and crispy. Drain on paper towels.
  3. Melt butter in a large skillet. Add sliced mushrooms, salt, and pepper. Sauté until mushrooms are tender and browned.
  4. Sprinkle flour over the sautéed mushrooms and cook for 1 minute. Gradually whisk in warmed milk, scraping up any browned bits from the bottom of the pan.
  5. Bring the béchamel to a simmer, stirring constantly until thickened. Reduce heat and simmer for 5 minutes, stirring occasionally. Stir in nutmeg, sherry (if using), and Parmesan cheese. Season to taste with salt and pepper.
  6. Toss the blanched green beans with the mushroom béchamel. Spread into a greased baking dish.
  7. Bake in a preheated oven (350°F/175°C) for 20 minutes, or until bubbly.
  8. Sprinkle the fried onions evenly over the casserole. Bake for another 10-15 minutes, or until the onions are golden brown and the casserole is heated through. Let stand for 5 minutes before serving.