If you love the rich, savory flavors of French onion soup, you’re going to fall head over heels for this French Onion Casserole. It takes everything we adore about the iconic soup—the deeply caramelized onions, the crusty bread, the melty cheese—and transforms it into a hearty, satisfying baked dish. Whether you’re serving it as a cozy main course or a show-stopping side, this casserole is sure to be a hit at the dinner table.
What makes this dish so special is the combination of flavors and textures. The sweetness of caramelized onions pairs beautifully with the nutty richness of Gruyère cheese, while chunks of crusty bread soak up the creamy sauce for an irresistibly soft interior with a perfectly golden top. It’s like wrapping yourself in a warm culinary hug!
Perfect for family dinners, holiday gatherings, or even as part of a potluck spread, this recipe is as versatile as it is delicious. It pairs wonderfully with roasted chicken, steak, or a crisp green salad, making it an all-around favorite. Plus, it’s easy to customize—add mushrooms for an earthy touch, use vegetable broth for a vegetarian option, or throw in some cooked chicken for a heartier take.
Scroll down for the full recipe and get ready to enjoy the ultimate comfort food with this rich, cheesy, and absolutely irresistible French Onion Casserole!
French Onion Casserole: A Comforting Twist on a Classic Dish
If you love the rich, savory flavors of French onion soup, you’re going to fall head over heels for this French Onion Casserole. It takes everything we adore about the iconic soup—the deeply caramelized onions, the crusty bread, the melty cheese—and transforms it into a hearty, satisfying baked dish. Whether you’re serving it as a cozy main course or a show-stopping side, this casserole is sure to be a hit at the dinner table.
Why This Recipe Works
This casserole brings the flavors of French onion soup to your oven in the most delicious way. The sweet and savory caramelized onions form the heart of the dish, delivering that signature depth of flavor. Gruyère cheese adds a nutty richness that melts beautifully, creating a golden, bubbling crust. Tossed with crusty bread and a creamy sauce, it’s everything you love about the soup—but easier to serve and perfect for sharing.
Great for Any Occasion
French Onion Casserole is incredibly versatile. It’s fancy enough for holiday gatherings yet simple enough for a casual weeknight dinner. Serve it as a side dish alongside roasted chicken, turkey, or beef, or let it shine as the star of the meal with a crisp green salad on the side. It’s also an excellent option for potlucks, as it travels well and reheats beautifully.
Tips for Success
- Caramelize Like a Pro: Patience is key! Take the time to slowly caramelize your onions to bring out their natural sweetness. Don’t rush this step—golden, deeply flavored onions make all the difference.
- Use the Right Cheese: Gruyère is the classic choice for French onion dishes, but you can also use Swiss or a combination of Gruyère and mozzarella for extra gooeyness.
- Choose Quality Bread: Day-old crusty bread, like a baguette or sourdough, works best. It soaks up the sauce without turning soggy, creating the perfect balance of textures.
Make It Your Own
This casserole is easy to customize based on your preferences:
- Add Protein: Stir in cooked shredded chicken, ground beef, or even crumbled sausage to make it a complete one-dish meal.
- Include Veggies: Sautéed mushrooms or spinach make great additions, adding extra flavor and nutrition.
- Go Vegetarian: Swap the beef broth for vegetable broth and skip the Worcestershire sauce for a vegetarian-friendly option.
Storage and Reheating
This casserole is a great make-ahead dish. Assemble it up to a day in advance, refrigerate, and bake it fresh when ready to serve. Leftovers can be stored in an airtight container in the fridge for up to 3 days. Reheat in the oven at 350°F (175°C) until warmed through to enjoy that melty, cheesy goodness all over again.
Perfect Pairings
French Onion Casserole pairs wonderfully with:
- A crisp green salad with a light vinaigrette to balance the richness.
- Roasted meats, such as chicken, pork tenderloin, or beef tenderloin.
- A glass of red wine like Cabernet Sauvignon or Pinot Noir to complement the savory flavors.
Treat your taste buds to the ultimate comfort food with this rich, cheesy, and absolutely irresistible French Onion Casserole! It’s a dish that will quickly become a family favorite.
French Onion Casserole Recipe
This French Onion Casserole is a warm, savory dish packed with caramelized onions, gooey cheese, and a rich, hearty flavor that’s perfect for dinner or as a side dish. Inspired by the classic French onion soup, this casserole transforms those iconic flavors into a comforting baked dish that pairs wonderfully with roasted meats or a crisp green salad.
Ingredients
- 3 large yellow onions, thinly sliced
- 3 tablespoons unsalted butter
- 2 tablespoons olive oil
- 1 teaspoon sugar
- 2 cloves garlic, minced
- 1 teaspoon dried thyme (or 2 teaspoons fresh thyme)
- 2 tablespoons all-purpose flour
- 1 cup beef broth (or vegetable broth for a vegetarian option)
- ½ cup heavy cream
- 1 teaspoon Worcestershire sauce
- 4 cups crusty bread, cubed (like baguette or sourdough)
- 2 cups shredded Gruyère cheese (or Swiss cheese)
- ½ cup shredded mozzarella cheese (optional for extra cheesiness)
- Salt and pepper, to taste
Instructions
- Caramelize the Onions:
In a large skillet, heat the butter and olive oil over medium heat. Add the sliced onions and sugar, and cook, stirring occasionally, for about 25–30 minutes, or until the onions are golden brown and caramelized. Add the garlic and thyme during the last 2 minutes of cooking. Season with salt and pepper. - Make the Sauce:
Sprinkle the flour over the onions and stir to coat. Cook for 1–2 minutes to eliminate the raw flour taste. Gradually pour in the beef broth while stirring to create a smooth sauce. Add the heavy cream and Worcestershire sauce, stirring until the mixture is thickened and creamy. Remove from heat. - Prepare the Casserole:
Preheat your oven to 375°F (190°C). In a greased 9×13-inch baking dish, layer half of the bread cubes evenly. Pour half of the onion mixture over the bread, then sprinkle with half of the Gruyère cheese. Repeat with the remaining bread, onions, and cheese. - Bake:
Cover the casserole with aluminum foil and bake for 20 minutes. Remove the foil and bake for an additional 10–15 minutes, or until the cheese is bubbly and golden. - Serve:
Let the casserole rest for 5 minutes before serving. Garnish with fresh thyme or parsley, if desired.
Tips:
- For a deeper flavor, deglaze the onions with a splash of white wine or sherry before adding the flour.
- Use day-old bread for the best texture—it will hold up better against the creamy sauce.
- Add a layer of sautéed mushrooms or cooked chicken for a heartier dish.
Enjoy this comforting and cheesy French Onion Casserole, a dish that brings the cozy flavors of French onion soup to your dinner table in a whole new way!
