Thanksgiving Side Dish: French Onion Green Bean Casserole

French onion green bean casserole pin

In the spirit of Thanksgiving, today we are sharing our Thanksgiving Side Dish Recipe: French Onion Green Bean Casserole. Who doesn’t love casserole, right? You can serve them ad one of the main dishes if you prefer non-traditional Thanksgiving dinners, but be sure to adjust the portions! You will need around an hour and a half to make this fantastic casserole.


For the onions:

  • 2 tablespoons butter
  • two large yellow onions thinly sliced lengthwise
  • salt and ground black pepper to taste
  • 1 tablespoon sherry vinegar

For the white sauce:

  • 2 tablespoons butter
  • two and a half tablespoons all-purpose flour
  • 2 1/2 cups milk
  • 1 pinch ground nutmeg
  • cayenne pepper to taste (optional)
  • 1/4 teaspoon ground thyme

For the topping:

  • 2 tablespoons melted butter
  • two-thirds cup panko bread crumbs
  • 2 pounds fresh green beans, trimmed
  • 4 ounces shredded Gruyere cheese, divided
  • 1/3 cup grated Parmesan cheese



  1. Preheat oven to 375 degrees F (190 degrees C). Grease a 9×13 inch casserole dish.
  2. Heat 2 tablespoons of butter in a large skillet over medium heat. Stir the onions into the pan; cook and stir until very soft and golden brown, about 15 minutes. Stir in sherry vinegar. Transfer to a small bowl, and reserve.
  3. In the same skillet, melt 2 more tablespoons butter. Whisk in 2 tablespoons flour. Stirring constantly, cook over medium heat until the flour smells like baked pie crust, about 3 minutes. Slowly whisk in milk, about 1/2 cup at a time, then whisk in nutmeg, cayenne pepper, and thyme. Bring to simmer, and cook until thickened, whisking constantly, 3 more minutes. Transfer to a bowl and reserve.
  4. Melt remaining 2 tablespoons butter in clean skillet; stir in panko until all crumbs are coated; reserve.
  5. Bring a large saucepan of salted water to a boil over medium heat, and boil beans until bright green and crisp but not raw tasting, 3 to 4 minutes. Drain very well.
  6. Spoon half of the caramelized onions into the prepared casserole dish; top with green beans. Season with salt and black pepper. Spread reserved white sauce over the green beans; sprinkle with half of the Gruyere cheese. Top with the rest of the onions, and use the back of a spoon to push onions down into sauce and cheese. Top with the buttered panko crumbs, the remaining Gruyere, and Parmesan cheese.
  7. Bake in the preheated oven until hot throughout and lightly browned, about 30 minutes. Let sit 10 minutes before serving.

French onion green bean casserole 2

Nutritional Info

French onion green bean casserole nutri info

You should also try our:

One Pot Pasta & Sausage