Ingredients:

  • 2 lbs Fresh Green Beans, trimmed and snapped
  • 1 tbsp Table Salt (for blanching water)
  • 1 Large bowl of ice water
  • 4 tbsp Unsalted Butter
  • 8 oz Mixed Mushrooms (Cremini and Shiitake), finely sliced
  • 2 medium Shallots, finely diced
  • 2 cloves Garlic, minced
  • ¼ cup All-Purpose Flour
  • 3 cups Whole Milk, warmed
  • ½ cup Vegetable or Chicken Stock (low sodium)
  • ½ tsp Nutmeg, freshly grated
  • 1 tsp Worcestershire Sauce
  • 1 tsp Kosher Salt, plus more to taste
  • ½ tsp Freshly Ground Black Pepper
  • 4 oz Extra Sharp Yellow Cheddar Cheese, grated
  • 2 oz Monterey Jack or Gruyère Cheese, grated
  • 1 cup Store-Bought Crispy Fried Onions
  • ½ cup Panko Breadcrumbs
  • 2 tbsp Unsalted Butter, melted

Instructions:

  1. Prep and Blanch the Green Beans: Bring a large pot of heavily salted water to a rolling boil. Prepare the ice bath. Blanch the trimmed green beans for 3–4 minutes until al dente. Immediately plunge them into the ice bath to stop the cooking process. Drain well and set aside.
  2. Build the Savoury Sauce (The Roux & Béchamel): Melt 4 tbsp of butter in the skillet over medium-high heat. Sauté the sliced mushrooms and shallots with a pinch of salt until they have released their liquid and browned beautifully (about 8-10 minutes).
  3. Add the minced garlic and cook for 1 minute until fragrant. Reduce heat to medium-low. Sprinkle in the flour, stirring constantly for 1–2 minutes (this is the roux).
  4. Whisking constantly: Slowly pour in the warm milk and stock. Increase the heat slightly and continue whisking until the sauce thickens and coats the back of a spoon (4–6 minutes).
  5. Remove the skillet from the heat. Stir in the grated cheeses, nutmeg, Worcestershire sauce, salt, and pepper until completely smooth. Taste and adjust seasoning.
  6. Assemble and Prepare the Topping: Preheat oven to 375°F (190°C). Grease the casserole dish lightly. Fold the blanched green beans into the cheese sauce, ensuring they are evenly coated. Pour the mixture into the prepared casserole dish.
  7. Prepare Topping: In a small bowl, combine the panko breadcrumbs and melted butter. Sprinkle the panko mixture over the casserole first. Reserve the store-bought fried onions for later.
  8. Bake and Finish: Bake the casserole for 25 minutes, or until the sauce is bubbly and the edges are slightly browned.
  9. Remove the casserole from the oven. Gently scatter the store-bought crispy onions over the top. Return to the oven for a final 8–10 minutes.
  10. Let the casserole rest on the counter for 5–10 minutes before serving. This allows the sauce to fully set up.