If you love the rich, comforting flavors of French onion soup but want a cozy, shareable dish that’s easier to serve, this French Onion Soup Casserole Recipe is your new best friend. It takes all the best elements of the classic soup—caramelized onions, gooey Swiss cheese, and that luscious creamy base—and transforms them into a delightful casserole perfect for family dinners or casual gatherings. Trust me, once you make this, you’ll want to keep it on repeat for weeknight meals or whenever you crave a warm hug on a plate.
Ingredients You’ll Need
This recipe is delightfully simple, made with essential ingredients that build layers of flavor and texture. Each component plays a crucial role in bringing that familiar French onion soup magic to casserole form.
- Butter or margarine: 2-3 tablespoons, for perfectly sautéing the onions to a soft, flavorful base.
- Sweet, white, or yellow onions: 3 large sweet or 4 medium white/yellow, sliced thinly; these develop sweetness and depth as they cook down.
- Shredded Swiss cheese: 2 cups (about 8 ounces), providing a nutty, melty topping that’s utterly irresistible.
- Cream of chicken soup: 1 undiluted can; alternatively, use cream of mushroom soup for a vegetarian twist and extra earthiness.
- Milk: 2/3 cup, to blend smoothly with the soup and create a creamy sauce.
- Soy sauce: 1 teaspoon, adds subtle umami richness boosting the onion flavor.
- French bread slices: 8 slices, for that satisfying crunch on top and soaking in all the lovely sauce.
- Pepper: to taste, for a gentle kick and balance.
How to Make French Onion Soup Casserole Recipe
Step 1: Slice the Onions
Begin by slicing your onions thinly. Yes, the classic “try not to cry” moment comes here, but it’s worth it! Thin slices will cook evenly and melt into the casserole, providing beautiful sweetness and soft texture.
Step 2: Sauté Onions in Butter
Melt the butter in a sauté pan set over medium heat, then add your sliced onions. Sauté them gently until they become translucent and soft. You can let them brown just a bit to add more depth of flavor, but don’t let them burn—just a lovely golden edge.
Step 3: Layer Onions and Cheese
In a shallow 2-quart casserole dish, build the base by layering your sautéed onions evenly. Sprinkle about two-thirds of your shredded Swiss cheese over the onions, then season with pepper to taste. This layering ensures cheesy pockets throughout the dish.
Step 4: Prepare the Creamy Sauce
In a small saucepan, combine the cream of chicken soup, milk, and soy sauce. Warm over medium heat while stirring frequently until the mixture blends smoothly. This sauce will soak into the onions and bread, imbuing the casserole with rich, savory flavor.
Step 5: Pour Sauce and Add French Bread
Pour your creamy mixture evenly over the onion and cheese layers in the casserole dish. Gently stir a bit to combine without breaking up the layers too much. Then arrange the French bread slices neatly on top; these will toast up beautifully during baking.
Step 6: Bake and Layer More Cheese
Bake the casserole uncovered at 350°F (175°C) for 15 minutes until the bread is nicely toasted and golden. Then press the bread slices down lightly into the sauce and sprinkle the remaining Swiss cheese over the top, preparing for the final bake.
Step 7: Final Bake for Gooey Goodness
Return the casserole to the oven and bake another 15 minutes. When you pull it out, the cheese should be melted, bubbly, and slightly golden—a perfect sign your French Onion Soup Casserole Recipe is ready to delight!
How to Serve French Onion Soup Casserole Recipe
Garnishes
Fresh herbs like finely chopped parsley or thyme add a pop of color and freshness to balance the rich flavors. A sprinkle of freshly cracked black pepper over the top right before serving also elevates the dish’s aroma beautifully.
Side Dishes
This casserole pairs wonderfully with crisp salads featuring a light vinaigrette to cut through its richness. Roasted vegetables or a simple green bean almondine also complement it well without overpowering the delicate onion and cheese notes.
Creative Ways to Present
Try serving individual portions of this French Onion Soup Casserole Recipe in small ramekins for a charming presentation at dinner parties. You can also scoop it onto toasted crostini for a great appetizer twist that everyone will love.
Make Ahead and Storage
Storing Leftovers
Leftover casserole keeps beautifully covered in the refrigerator for up to 3 days. The flavors meld even more overnight, making for a delicious second helping that tastes just as indulgent as the first.
Freezing
You can freeze this casserole before baking. Cover tightly with foil and freeze for up to 2 months. When ready to enjoy, thaw overnight in the fridge and bake as directed, adding a few extra minutes if needed.
Reheating
To reheat, warm portions in the oven at 350°F until heated through and the cheese is again bubbly. Microwaving works in a pinch, but the oven preserves the casserole’s texture best.
FAQs
Can I use a different type of cheese?
Absolutely! While Swiss cheese adds a lovely nutty flavor, Gruyere, mozzarella, or even cheddar can be used depending on your preference. Just choose a cheese that melts well.
Is there a vegetarian version of this casserole?
Yes, simply use cream of mushroom soup instead of cream of chicken to keep it vegetarian-friendly without losing that creamy goodness.
Can I make this gluten-free?
Definitely! Substitute the French bread with gluten-free bread slices, and ensure the soup you use is gluten-free as well.
What type of onions work best?
Sweet onions are ideal for their natural sweetness, but white or yellow onions work fine too. You can mix types for a more complex flavor if you like.
How long can I keep leftovers in the fridge?
Leftovers are best eaten within 3 days for optimal freshness and safety, but the casserole often tastes even better the next day!
Final Thoughts
This French Onion Soup Casserole Recipe truly captures the heartwarming essence of a classic soup in a form that’s shareable, soothing, and utterly delicious. Whether you’re making it for a family dinner or entertaining friends, it’s guaranteed to be a crowd-pleaser. So grab your onions and cheese, and get ready to whip up a comforting casserole that feels like a hug from the inside out.
Print
French Onion Soup Casserole Recipe
- Prep Time: 15 minutes
- Cook Time: 30 minutes
- Total Time: 45 minutes
- Yield: 6 servings
- Category: Casserole
- Method: Baking
- Cuisine: French-American
- Diet: Vegetarian
Description
A comforting and savory French Onion Soup Casserole featuring caramelized onions layered with creamy soup and melted Swiss cheese, topped with toasted French bread. This easy casserole combines classic soup flavors with a baked dish perfect for a cozy meal.
Ingredients
Ingredients
- 2–3 tablespoons butter or margarine
- 3 large sweet onions or 4 medium white or yellow onions, sliced
- 2 cups shredded Swiss cheese (8 oz.)
- 1 can cream of chicken soup, undiluted (or cream of mushroom soup for vegetarian)
- 2/3 cup milk
- 1 teaspoon soy sauce
- 8 slices French bread
- Pepper to taste
Instructions
- Slice the onions: Peel and thinly slice the onions carefully, prepping them for sautéing.
- Sauté the onions: Melt butter in a sauté pan over medium heat. Add the sliced onions and cook until they are translucent with slight browning, which enhances their sweetness.
- Assemble the base layer: In a shallow 2-quart casserole dish, layer the sautéed onions evenly, sprinkle 2/3 of the shredded Swiss cheese on top, and season with pepper to taste.
- Prepare the sauce: In a saucepan, combine the undiluted cream of chicken soup, milk, and soy sauce. Heat while stirring until well blended. Pour this mixture over the layered onions and cheese gently to combine all flavors.
- Add the bread topping: Arrange the 8 slices of French bread over the casserole surface. Bake uncovered at 350°F (175°C) for 15 minutes, allowing the bread to become nicely toasted.
- Finish the topping: Press the toasted bread slices down into the creamy sauce and sprinkle the remaining Swiss cheese evenly over the top.
- Bake to melt the cheese: Return the casserole to the oven and bake for an additional 15 minutes, until the cheese is melted, bubbly, and lightly browned.
Notes
- For a vegetarian option, substitute cream of chicken soup with cream of mushroom soup.
- Use sweet onions for a milder, sweeter flavor or white/yellow onions for a more traditional taste.
- If you prefer a crispier bread topping, broil the bread slices briefly before assembling.
- Adding a pinch of thyme or fresh herbs can enhance the flavor.
- Serve hot as a hearty main dish or comfort food side.
