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Green Bean Casserole from Scratch

Skip the canned soup and build a green bean casserole from scratch with fresh beans, sliced mushrooms, and a rich homemade cream sauce.
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Prep Time 20 minutes
Cook Time 35 minutes
Rest Time 5 minutes
Total Time 1 hour
Servings: 8
Ingredients Equipment Method Notes

Ingredients
  

  • 2 lbs fresh green beans trimmed and cut into 2-inch pieces
  • 12 oz cremini mushrooms cleaned and sliced 1/4-inch thick
  • 4 tbsp unsalted butter divided into 1 tbsp and 3 tbsp portions
  • 3 cloves garlic minced
  • 3 tbsp all-purpose flour unbleached
  • 1 cup low-sodium chicken broth warm
  • 1 cup heavy cream room temperature
  • 0.5 tsp kosher salt plus more for boiling water
  • 0.25 tsp black pepper freshly cracked
  • 0.25 tsp nutmeg freshly grated
  • 1.5 cups French fried onions divided

Equipment

  • 9x13-inch Baking Dish
  • Large stockpot
  • 12-inch Skillet
  • Slotted spoon
  • Large mixing bowl

Method
 

  1. Preheat your oven to 375°F (190°C) and grease a 9x13-inch baking dish with butter.
  2. Fill a large stockpot with 4 quarts of water, stir in 2 tablespoons of kosher salt, and bring to a rolling boil over high heat.
  3. Prepare an ice bath by filling a large mixing bowl with cold water and ice cubes.
  4. Add trimmed green beans to the boiling water and cook for 4 minutes until vibrant green and tender-crisp.
  5. Transfer green beans immediately to the ice bath using a slotted spoon.
  6. Drain green beans after 3 minutes and dry them thoroughly between paper towels.
  7. Melt 1 tablespoon of butter in a 12-inch skillet over medium-high heat.
  8. Add sliced cremini mushrooms and cook for 6 to 8 minutes without moving them constantly, until deep brown and all released liquid evaporates.
  9. Add remaining 3 tablespoons of butter and minced garlic to the skillet, cooking for 1 minute until fragrant.
  10. Sprinkle flour over the mushrooms and stir constantly for 2 minutes to cook the roux.
  11. Whisk in chicken broth gradually, scraping up any browned bits from the skillet bottom.
  12. Pour in heavy cream, salt, black pepper, and nutmeg, then bring sauce to a gentle simmer.
  13. Simmer for 4 to 5 minutes, stirring continuously, until sauce thickens enough to coat the back of a spoon.
  14. Fold dried green beans directly into the skillet sauce until fully coated.
  15. Transfer mixture into prepared baking dish and spread into an even layer.
  16. Bake uncovered at 375°F for 20 minutes until sauce bubbles around dish edges.
  17. Scatter French fried onions evenly across the top and bake for 5 additional minutes until golden brown.
  18. Remove casserole from oven and let rest 5 minutes before serving.

Notes

To assemble this dish 24 hours ahead, combine blanched beans and mushroom sauce in your baking dish, cover tightly with foil, and store in the refrigerator. Add 5 minutes to the initial bake time before adding onion topping.
If using a glass baking dish instead of ceramic or metal, lower oven temperature to 350°F and increase bake time by 5 minutes to ensure uniform heating without scorching edges.
For extra crispness, toss half of the crispy onions into the internal bean mixture before baking, reserving the rest for the top layer.