Ingredients:

  • 5 lbs fresh green beans, trimmed
  • 2 tsp table salt (for blanching water)
  • 4 tbsp (56 g) unsalted butter
  • 1 large shallot, finely diced
  • 8 oz (225 g) cremini (brown) mushrooms, or a mix of wild mushrooms, sliced thinly
  • 2 cloves garlic, minced
  • 1/4 cup (30 g) all-purpose flour
  • 2 cups (475 ml) whole milk, warmed slightly
  • 1/2 cup (120 ml) low-sodium chicken or vegetable stock
  • 1/2 cup (120 ml) heavy cream
  • 1/4 cup (30 g) finely grated Parmesan cheese
  • 1 tsp smoked paprika (optional)
  • 1/4 tsp freshly grated nutmeg
  • Salt and freshly ground black pepper, to taste
  • 5 cups (120 g) pre-made French fried onions

Instructions:

  1. Preheat oven to 375°F (190°C). Lightly grease a 9 x 13 inch casserole dish.
  2. Blanch the Beans: Bring a large pot of heavily salted water to a rolling boil. Drop the trimmed green beans in and cook for 3-5 minutes until they are bright green and al dente (still have a bite).
  3. Shock the Beans: Immediately drain the beans and plunge them into a large bowl of ice water. This halts the cooking process and locks in the vibrant color. Drain thoroughly once cool and set aside.
  4. Sauté Aromatics: Melt the butter in a medium saucepan over medium heat. Add the diced shallot and cook until softened (about 3 minutes).
  5. Cook Mushrooms: Add the sliced mushrooms to the pan. Increase the heat slightly and sauté until all the mushroom liquid has evaporated and the mushrooms have browned slightly (8–10 minutes). Stir in the minced garlic for the final minute.
  6. Make the Roux: Sprinkle the flour over the mushroom mixture. Stir continuously for 1–2 minutes; this cooks out the raw flour taste, creating a blonde roux.
  7. Whisk in Liquid: Gradually pour in the warm milk and the stock, whisking constantly to prevent lumps. The sauce will thicken rapidly.
  8. Simmer and Season: Bring the sauce to a gentle simmer, stirring occasionally, until it coats the back of a spoon (about 5 minutes). Reduce heat to low.
  9. Finish the Sauce: Stir in the heavy cream, Parmesan cheese, smoked paprika (if using), nutmeg, salt, and pepper. Taste and adjust seasoning; the sauce should be robustly seasoned.
  10. Combine: Transfer the blanched green beans to a large mixing bowl. Pour the creamy mushroom sauce over the beans and toss gently until every bean is coated.
  11. Bake (Initial): Transfer the mixture to the prepared casserole dish. Bake uncovered for 15 minutes, allowing the beans to heat through and the sauce to bubble.
  12. Add Topping and Finish: Remove the casserole from the oven. Evenly sprinkle the French fried onions over the top. Return to the oven and bake for another 10–15 minutes, or until the topping is golden brown and the sauce is fully heated and bubbling.
  13. Rest and Serve: Allow the casserole to rest for 5–10 minutes before serving.