Ingredients:

  • 680 g / 1.5 lbs Fresh Green Beans (trimmed, preferably Haricots Verts)
  • 3 Litres Cold Water (for blanching)
  • 1 tbsp Kosher Salt (for blanching water)
  • 4 tbsp (56 g) Unsalted Butter
  • 200 g / 7 oz Cremini Mushrooms (sliced thinly)
  • 1 large Shallot (finely minced)
  • 2 cloves Garlic (minced)
  • 4 tbsp (50 g) All-Purpose Flour (Plain Flour)
  • 475 ml / 2 cups Chicken or Vegetable Stock (low sodium, warmed)
  • 240 ml / 1 cup Whole Milk or Half-and-Half (warmed)
  • 60 ml / ¼ cup Heavy Cream (Double Cream)
  • 1 tsp Worcestershire Sauce
  • ½ tsp Freshly Grated Nutmeg
  • Salt and Freshly Ground Black Pepper (to taste)
  • 1½ cups (approx. 150 g) Crispy Fried Onions
  • 2 tbsp (28 g) Unsalted Butter (melted, for mixing with topping)

Instructions:

  1. Prep the Green Beans: Bring the 3 litres of water and 1 tbsp salt to a rolling boil in the stockpot. Add the trimmed green beans and cook for exactly 3–4 minutes until they turn bright green and are just tender (al dente).
  2. Chill: Immediately drain the beans and plunge them into a prepared ice bath to stop the cooking process and set the color. Drain thoroughly and set aside.
  3. Sauté Aromatics: Melt the butter in the large skillet over medium heat. Add the sliced mushrooms and minced shallot. Sauté until the moisture has evaporated and the mushrooms are deeply browned (about 8–10 minutes). Add the minced garlic during the last minute.
  4. Make the Roux: Sprinkle the flour over the mushroom mixture. Stir continuously for 2 minutes to cook out the raw flour taste.
  5. Whisk in Liquid: Gradually whisk in the warm stock until fully incorporated and smooth. Then, gradually whisk in the warm milk and heavy cream.
  6. Simmer and Season: Bring the sauce to a gentle simmer, whisking occasionally, until it has thickened enough to coat the back of a spoon (about 5 minutes). Reduce heat to low. Stir in the Worcestershire sauce and nutmeg. Season generously with salt and pepper.
  7. Preheat and Combine: Preheat the oven to 190°C / 375°F. Gently fold the blanched green beans into the cream sauce until they are evenly coated. Pour the mixture into the prepared baking dish.
  8. Initial Bake: Bake uncovered for 15 minutes, until the casserole is bubbling hot.
  9. Prepare and Apply Topping: While the casserole bakes, toss the crispy fried onions with the 2 tbsp of melted butter. Remove the casserole from the oven, spread the buttered crispy onions evenly over the top, and return to the oven for another 8–10 minutes, or until the topping is golden brown and crunchy.
  10. Rest and Serve: Let the casserole rest for 5–10 minutes before serving.