Ingredients:

  • 3 large Shallots (or small yellow onions), thinly sliced
  • 1/4 cup All-purpose flour (for dredging shallots)
  • 1/2 teaspoon Salt (for dredging)
  • 3 cups Neutral oil (Canola or Vegetable), for deep frying
  • 2 pounds Fresh Green Beans (Haricot Verts preferred), trimmed
  • 4 tablespoons Unsalted butter
  • 4 tablespoons All-purpose flour (for roux)
  • 8 ounces Cremini Mushrooms (Baby Bella), thinly sliced
  • 2 cloves Garlic, minced
  • 1 cup Chicken or Vegetable Stock, low sodium
  • 1 1/2 cups Whole Milk or Half-and-Half, room temperature
  • 1 teaspoon Worcestershire Sauce
  • 1 teaspoon Fresh Thyme Leaves, finely chopped (optional)
  • Salt and Black Pepper, to taste
  • Pinch freshly grated Nutmeg

Instructions:

  1. Preheat the oven to 375°F (190°C). Lightly grease a 9x13 inch or 2-quart baking dish.
  2. Blanch the Beans: Bring a large pot of salted water to a rolling boil. Drop the trimmed green beans into the water and cook for 4–5 minutes until vibrant green and tender-crisp ('al dente'). Immediately transfer the beans to a large bowl of ice water to shock them and stop the cooking. Drain well and set aside.
  3. Prepare Shallots: Slice shallots thinly. Toss them with 1/4 cup flour and 1/2 teaspoon of salt until lightly coated.
  4. Fry Shallots: Heat 3 cups of neutral oil in a Dutch oven or deep skillet over medium-high heat until it reaches 325–350°F (160–175°C). Working in small batches, carefully drop the floured shallots into the hot oil. Fry for 3–5 minutes, stirring gently, until deep golden brown and crispy.
  5. Drain and Reserve: Use a slotted spoon to remove the shallots and immediately spread them in a single layer on a prepared wire rack/paper towels. Sprinkle lightly with extra salt. Reserve 2/3 of the shallots for topping and 1/3 to stir into the sauce.
  6. Sauté Mushrooms and Garlic: In a medium saucepan, melt the 4 tablespoons of butter. Add sliced mushrooms and sauté until they brown slightly (about 5 minutes). Add the minced garlic and cook for 1 minute.
  7. Make the Roux: Sprinkle the 4 tablespoons of flour over the mushroom mixture. Stir continuously for 1–2 minutes to cook out the raw flour taste.
  8. Thicken Sauce: Gradually whisk in the stock until smooth, followed by the room-temperature milk/half-and-half. Bring the mixture to a gentle simmer, stirring constantly, until the sauce thickens enough to coat the back of a spoon (5–8 minutes).
  9. Finish Sauce: Stir in the Worcestershire sauce, fresh thyme (if using), nutmeg, and salt and pepper to taste. Remove from heat.
  10. Combine: Gently fold the blanched green beans and the reserved 1/3 portion of the crispy shallots into the scratch mushroom sauce. Taste and adjust seasoning.
  11. Bake: Pour the mixture into the prepared baking dish. Bake, uncovered, for 15 minutes, until the sauce is bubbly around the edges.
  12. Top and Finish: Remove the casserole from the oven. Evenly scatter the remaining 2/3 of the crispy shallots over the top. Return to the oven and bake for an additional 5 minutes, or until the topping is hot and deeply golden.
  13. Rest: Allow the casserole to rest for 5–10 minutes before serving.