Ingredients:

  • 2 lbs (900 g) Frozen or Fresh Green Beans
  • 5 cups (150 g) Crispy Fried Onions
  • 1 tsp (5 g) Butter (for greasing)
  • 4 Tbsp (55 g) Unsalted Butter
  • 1 large (100 g) Shallots or Small Yellow Onion, finely minced
  • 8 oz (225 g) Cremini or Button Mushrooms, sliced or roughly chopped
  • 4 Tbsp (45 g) All-Purpose Flour
  • 1 cup (240 ml) Chicken or Vegetable Stock, low sodium
  • 1 cup (240 ml) Whole Milk, full-fat
  • 1 tsp (5 ml) Worcestershire Sauce (Optional)
  • 1/2 tsp (2 ml) Dried Thyme
  • 1 tsp (5 g) Kosher Salt
  • 1/2 tsp (2 g) Freshly Ground Black Pepper

Instructions:

  1. Preheat the oven to 375°F (190°C). Lightly grease a 9x13 inch casserole dish with butter.
  2. Prepare the Beans: If using fresh beans, blanch them in boiling, salted water for 4–5 minutes until just tender-crisp. Immediately drain and plunge into ice water. If using frozen, skip blanching. Place the prepared green beans into the greased casserole dish.
  3. Sauté Aromatics: Melt 2 tablespoons of the butter in a saucepan over medium heat. Add the minced shallots/onion and cook until translucent, about 3 minutes.
  4. Sear Mushrooms: Add the sliced mushrooms. Increase heat to medium-high and cook, stirring occasionally, until the mushrooms release their liquid and begin to brown (about 6–8 minutes). Season lightly. Remove the mushroom mixture and set aside.
  5. Make the Roux: Return the pan to medium heat and melt the remaining 2 tablespoons of butter. Whisk in the flour and cook for 1–2 minutes, stirring constantly, until the mixture smells nutty.
  6. Whisk in Liquids: Slowly pour in the cold stock, whisking continuously to prevent lumps. Once smooth, slowly whisk in the milk. Bring the sauce to a gentle simmer, whisking occasionally, until it thickens to coat the back of a spoon (about 5 minutes).
  7. Finish Sauce: Stir in the dried thyme, Worcestershire sauce (if using), and adjust salt and pepper to taste. The sauce should taste slightly too salty before combining with the beans.
  8. Assemble: Fold the cooked mushroom/shallot mixture back into the sauce. Pour the mushroom sauce evenly over the green beans in the casserole dish and toss gently to ensure coating.
  9. Initial Bake: Bake uncovered for 15 minutes, until the sauce is bubbly around the edges.
  10. Finish the Topping: Remove the casserole from the oven. Sprinkle the crispy fried onions evenly over the top. Return to the oven for 5–8 minutes, or until the topping is golden brown and the dish is piping hot. Let stand for 5 minutes before serving.