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Green Bean Casserole From Scratch - Cozy, Classic, and Made the Right Way

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Prep Time 20 minutes
Cook Time 40 minutes
Total Time 1 hour
Servings: 8 servings
Ingredients Method

Ingredients
  

  • Green beans: 1 1/2 pounds, trimmed and cut into 2-inch pieces
  • Olive oil: 2 tablespoons
  • Unsalted butter: 3 tablespoons
  • Cremini or button mushrooms: 12 ounces, finely sliced
  • Shallots: 2 large, thinly sliced (plus 1 extra for topping, optional)
  • Garlic: 3 cloves, minced
  • All-purpose flour: 3 tablespoons
  • Chicken or vegetable broth: 1 1/2 cups
  • Heavy cream or half-and-half: 3/4 cup
  • Dijon mustard: 1 teaspoon
  • Soy sauce or tamari: 1 teaspoon (for umami)
  • Fresh thyme leaves: 1 teaspoon (or 1/2 teaspoon dried)
  • Nutmeg: A pinch (optional but classic)
  • Kosher salt and black pepper: To taste
  • Panko breadcrumbs: 3/4 cup
  • Parmesan cheese: 1/3 cup, finely grated (optional but great for the topping)
  • Neutral oil: 1/2 cup (for crisping shallots, if making crispy shallot topping)
  • Cooking spray or butter: For greasing the baking dish

Method
 

  1. Heat the oven: Set to 375°F (190°C). Grease a 9x13-inch baking dish.
  2. Blanch the beans: Bring a large pot of salted water to a boil. Add green beans and cook 4–5 minutes until bright green and just tender. Drain and plunge into an ice bath to stop cooking. Drain again and set aside.
  3. Sauté the mushrooms: Warm 2 tablespoons olive oil and 1 tablespoon butter in a large skillet over medium-high heat. Add mushrooms and a pinch of salt. Cook, stirring occasionally, until they release liquid and it evaporates, about 7–9 minutes. They should be browned at the edges.
  4. Add aromatics: Reduce heat to medium. Stir in sliced shallots and cook 2–3 minutes until soft. Add garlic and thyme, and cook 30 seconds until fragrant.
  5. Make the roux: Push vegetables to the edges of the pan. Melt remaining 2 tablespoons butter in the center. Sprinkle in flour and whisk, cooking 1 minute to remove raw taste.
  6. Build the sauce: Slowly whisk in broth until smooth. Simmer 2–3 minutes until slightly thickened. Stir in cream, Dijon, soy sauce, nutmeg, and several grinds of black pepper. Simmer another 2–3 minutes until the sauce lightly coats a spoon. Taste and adjust salt and pepper. It should be well-seasoned.
  7. Combine: Add blanched green beans to the skillet and toss to coat. If your skillet isn’t large, mix in a big bowl.
  8. Make the topping: In a small bowl, mix panko with Parmesan (if using) and a pinch of salt and pepper. Drizzle with a little olive oil or melted butter and toss to moisten. For extra crunch, see the crispy shallot option below.
  9. Assemble: Transfer the bean mixture to the baking dish. Sprinkle evenly with the breadcrumb mixture.
  10. Bake: Bake 18–22 minutes, until bubbling at the edges and the top is golden. If needed, broil 1–2 minutes for extra color—watch closely.
  11. Optional crispy shallots: While it bakes, heat 1/2 cup neutral oil in a small skillet over medium. Add very thinly sliced shallot (1 large) and cook, stirring, until light golden, 4–6 minutes. Remove with a slotted spoon to a paper towel and salt lightly. Scatter over the casserole just before serving for maximum crunch.
  12. Rest and serve: Let the casserole rest 10 minutes so it sets slightly. Top with crispy shallots (if using) and serve warm.