Ingredients:

  • 1 kg (2.2 lbs) Fresh Green Beans (trimmed)
  • 3 L (12 cups) Water
  • 3 tbsp (45 mL) Kosher Salt (for blanching water)
  • 6 tbsp (85 g) Unsalted Butter
  • 1 cup (100 g) Yellow Onion or Shallots, finely diced
  • 200 g (7 oz) Cremini Mushrooms, thinly sliced
  • 1/4 cup (30 g) All-Purpose Flour
  • 1 cup (240 mL) Chicken or Vegetable Stock (low sodium)
  • 2 cups (480 mL) Whole Milk (or half-and-half)
  • 1 tsp Smoked Paprika
  • 1/2 tsp Dried Thyme
  • 1/4 tsp Nutmeg, freshly grated
  • 1 tsp (5 g) Kosher Salt, plus more to taste
  • 1/2 tsp Freshly Ground Black Pepper
  • 1/2 cup (50 g) Gruyère or Sharp White Cheddar Cheese, grated (optional)
  • 1 tbsp (15 g) Unsalted Butter, melted (for topping)
  • 2 cups (100 g) Fried Onions (store-bought)
  • 1/2 cup (60 g) Panko Breadcrumbs

Instructions:

  1. Prepare the Beans (Blanching): Bring 3 L of heavily salted water to a rolling boil. Add the trimmed green beans and cook for exactly 3–4 minutes until crisp-tender (al dente). Immediately transfer the beans to a waiting ice bath to halt the cooking process. Drain thoroughly and set aside.
  2. Begin the Sauce Base: Melt the 6 tbsp butter in the saucepan over medium heat. Add the diced onions/shallots and mushrooms. Sauté until the moisture evaporates and the mushrooms are deeply golden brown (about 8–10 minutes). Sprinkle the flour over the mixture. Whisk constantly for 1–2 minutes to cook out the raw flour taste.
  3. Build the Béchamel: Slowly pour in the cold stock, whisking continuously to prevent lumps. Gradually whisk in the whole milk. Bring the mixture to a gentle simmer, whisking frequently until the sauce thickens and coats the back of a spoon (about 5–7 minutes). Remove from heat. Stir in smoked paprika, thyme, nutmeg, salt, pepper, and the grated cheese (if using) until fully melted and smooth.
  4. Assemble and Initial Bake: Fold the blanched, drained green beans gently into the prepared creamy sauce until evenly coated. Pour the mixture into a prepared 9x13 inch casserole dish. Bake in a preheated oven at 190°C (375°F) for 15–20 minutes, or until the casserole is hot and bubbling around the edges.
  5. Finish the Topping and Serve: In a small bowl, combine the store-bought crispy onions, panko breadcrumbs, and melted butter. Remove the casserole from the oven, sprinkle the topping mixture evenly over the top, and return to the oven for a final 10–15 minutes, or until the topping is golden brown and supremely crunchy. Let the casserole rest for 5–10 minutes before serving.