Ingredients:

  • 5 lb (700 g) Fresh Green Beans (preferably Haricots Verts), trimmed
  • 1 tbsp (15 ml) Kosher Salt (for blanching water)
  • 4 tbsp (55 g) Unsalted Butter
  • 2 medium (100 g) Shallots, finely minced
  • 1 lb (450 g) Mixed Mushrooms (Cremini/Chestnut and Shiitake recommended), thinly sliced
  • 2 cloves Garlic, minced
  • 4 tbsp (50 g) All-Purpose Flour
  • 1 cup (240 ml) Low-Sodium Chicken or Vegetable Stock
  • 5 cups (360 ml) Whole Milk or Half-and-Half (room temperature is best)
  • 1 tsp (5 ml) Fresh Thyme leaves, chopped
  • ½ tsp (2.5 ml) Worcestershire Sauce (optional)
  • Pinch of Freshly Grated Nutmeg
  • 1 tsp (5 ml) Kosher Salt, plus more to taste
  • ½ tsp (2.5 ml) Freshly Ground Black Pepper
  • 6 oz (170 g) High-Quality Store-Bought Crispy Fried Onions
  • 1 tbsp (15 ml) Fresh Parsley, chopped (for garnish)

Instructions:

  1. Prep the Beans: Bring a large pot of heavily salted water to a rolling boil. Add the trimmed green beans and blanch for 3 to 4 minutes until they are bright green and al dente. Immediately drain the beans and plunge them into an ice bath to stop the cooking process and set the color. Drain thoroughly and set aside.
  2. Build the Velouté Base (The Sauté): Melt the butter in a large skillet over medium heat. Add the minced shallots and sauté for 3 minutes until softened. Add the sliced mushrooms and a pinch of salt. Cook until the mushrooms have released their liquid and it has completely evaporated, leaving them well-browned and concentrated (about 8–10 minutes). Stir in the minced garlic and thyme; cook for 1 minute until fragrant.
  3. Create the Roux and Thicken the Sauce: Sprinkle the flour over the mushroom mixture and stir continuously for 2 minutes to cook out the raw flour taste (creating the roux). Slowly whisk in the cold stock, ensuring no lumps form. Gradually whisk in the room-temperature milk/half-and-half. Bring the sauce to a gentle simmer, stirring constantly, until it thickens sufficiently to coat the back of a spoon (about 5 minutes). Reduce heat to low.
  4. Season and Assemble: Remove the sauce from the heat. Stir in the Worcestershire sauce, nutmeg, salt, and pepper. Taste and adjust seasoning. Gently fold the blanched green beans into the finished sauce until they are fully coated. Pour the mixture into the prepared 9x13 inch baking dish.
  5. Bake and Finish: Preheat oven to 375°F (190°C). Bake the casserole, uncovered, for 20 minutes, allowing the sauce to bubble and the flavors to meld. Remove the dish from the oven. Sprinkle the crispy fried onions evenly over the top. Return the casserole to the oven for a final 5 to 8 minutes, just until the onions are heated through and the edges of the casserole are golden brown. Let rest for 5 minutes before serving. Garnish with fresh parsley.