If you love the rich, savory depth of a classic French Onion Soup and the gooey, cheesy comfort of homemade mac and cheese, this French Onion Soup Mac and Cheese is about to become your new obsession. It combines deeply caramelized onions, a velvety Gruyère cheese sauce, and a crunchy, buttery crouton topping for a meal that tastes like a fancy bistro dinner but feels like a warm hug.
Inspired by Jeff Mauro’s famous mashup, my version leans into that authentic “soup” flavor by incorporating savory beef broth and fresh thyme right into the creamy cheese sauce. It’s rich, nutty, and absolutely packed with flavor—the perfect main dish for a cozy night in or a show-stopping side for your next holiday feast.
Key Takeaways
- Best of Both Worlds: You get the salty, beefy richness of the soup and the creamy indulgence of pasta in one bite.
- Patience Pays Off: The secret is in the onions—cooking them “low and slow” until they are deep golden brown is non-negotiable for that authentic flavor.
- Cheese Matters: We use real Gruyère cheese for that classic nutty melt, just like the layer on top of the soup crock.
- Crunchy Finish: Instead of breadcrumbs, we use torn baguette pieces tossed in butter to mimic the “crouton” topping of the soup.
- If you love hearty, cheesy pasta dishes, you absolutely need to try my The Ultimate Chili Mac and Cheese next—it’s another crowd favorite!
Why You’ll Love This French Onion Mac and Cheese
- Deep, Complex Flavor: The addition of a splash of sherry and beef broth gives this mac and cheese a depth that regular recipes just can’t match.
- Texture Heaven: The gooey cheese pull combined with the crispy, buttery bread topping is pure satisfaction.
- Sophisticated Comfort: It feels upscale enough for a dinner party but is humble enough for a Tuesday night.
- Vegetarian-Friendly Option: You can easily swap the beef broth for a rich vegetable stock or mushroom broth if you prefer, though the beef flavor is traditional.
- Smells Amazing: Your entire kitchen will smell like caramelized onions and browned butter—basically the best candle scent ever.
- Make-Ahead Friendly: You can caramelize the onions a day or two in advance to save time on cooking night.
- For another baked pasta that brings the cozy vibes, check out my Easy Baked Spaghetti which is perfect for feeding a crowd.
Food or Cultural Background
French Onion Soup is one of those timeless classics that relies on simple, humble ingredients—onions, broth, and stale bread—transformed by time and technique into something luxurious. Combining it with American-style mac and cheese might sound wild, but it makes perfect sense. The sweetness of the caramelized onions cuts through the rich fat of the cheese, and the pasta acts as the perfect vehicle for all that sauce.
I remember the first time I made this; I was craving soup but needed something heartier to feed the family. I decided to fold my “soup” base into a Mornay sauce, and the result was magic. It’s a dish that bridges the gap between European elegance and American comfort food. It’s rich, unpretentious, and deeply satisfying—kind of like my Slow Cooker Beef Stew, which also relies on that deep, savory beef flavor.
Ingredients for French Onion Mac and Cheese
| Ingredient | Notes/Substitutes |
|---|---|
| Yellow Onions | You need about 3-4 large ones. They shrink down a lot when caramelized. Sweet onions (Vidalia) work too. |
| Pasta | Cavatappi (corkscrews) is my favorite because it holds the thick sauce, but elbows or shells work great. |
| Gruyère Cheese | The classic choice for French Onion Soup. It’s nutty and melts beautifully. Don’t skip it! |
| Mozzarella/White Cheddar | Gruyère can be strong, so I mix it with mild Mozzarella or Sharp White Cheddar for balance and extra “pull.” |
| Beef Broth | Adds that signature dark, savory “soup” color and flavor to the white sauce. |
| Dry Sherry | Used to deglaze the onion pan. You can sub with a splash of white wine or apple cider vinegar if needed. |
| Fresh Thyme | Essential for that earthy, herbal note. Dried thyme works in a pinch (use 1/3 the amount). |
| Baguette/French Bread | Torn into bite-sized pieces for the topping. |
If you have extra pasta left over, save it to make my Creamy Chicken Garlic Pasta Recipe later in the week!
Equipment Needed
- Dutch Oven or Large Pot: For boiling pasta and mixing everything.
- Large Skillet: For caramelizing the onions (surface area helps them cook faster).
- Cheese Grater: Always grate your own cheese for the smoothest sauce!
- 9×13 Baking Dish: Or a large cast-iron skillet if you want a rustic look.
- Whisk: For getting that roux nice and smooth.
How to Make French Onion Mac and Cheese Step-by-Step
- Caramelize the Onions: Melt butter in a large skillet over medium heat. Add the sliced onions and a pinch of salt. Cook, stirring occasionally, for 30-40 minutes until they are deep golden brown and jammy. Don’t rush this!
- Deglaze: Pour in the sherry (or a splash of beef broth) and scrape up all those delicious brown bits (the fond) from the bottom of the pan. Stir in fresh thyme and set aside.
- Boil Pasta: Cook your pasta in salted water until it’s al dente (usually 1-2 minutes less than the box says). Drain and set aside.
- Make the Roux: In a large pot, melt butter and whisk in the flour. Cook for 1-2 minutes until bubbly and golden to cook out the raw flour taste.
- Build the Sauce: Slowly whisk in the beef broth and milk (or cream). Simmer for 3-5 minutes until thickened enough to coat the back of a spoon.
- Melt the Cheese: Remove from heat and stir in the grated Gruyère and Mozzarella until smooth. Season with salt, pepper, and a pinch of nutmeg.
- Combine: Fold the cooked pasta and 3/4 of the caramelized onions into the cheese sauce.
- Bake: Pour into a baking dish. Top with the remaining onions and torn baguette pieces (tossed in a little melted butter). Bake at 375°F (190°C) for 20-25 minutes until bubbly and the bread is golden and crisp.
While the onions are caramelizing, you might have time to prep a quick side, or if you’re planning your next pasta night, check out my Homemade Lasagna Recipe for another baked classic.
Expert Tips for the Best Results
- Grate Your Own Cheese: Pre-shredded cheese is coated in anti-caking agents (like potato starch) that can make your sauce gritty. Buy the block!
- Low and Slow Onions: If you try to burn the onions on high heat, they’ll be bitter. You want them sweet and soft. If they start sticking, add a splash of water.
- Sauce Consistency: The sauce might look a little loose before baking—that’s good! The pasta will absorb moisture in the oven. If it’s too thick now, it will be dry later.
- The Bread Hack: Toss your torn bread pieces in melted butter and a little garlic powder before putting them on top. It ensures every crouton is flavorful and crispy.
- Beef Broth Boost: Use a high-quality beef stock or broth concentrate (like Better Than Bouillon) for a richer color and flavor.
- If you love rich, creamy sauces, you’ll definitely enjoy the technique in my Philly Cheesesteak Mac and Cheese too.
What to Serve With French Onion Mac and Cheese
- A Crisp Green Salad: You need something acidic and fresh to cut through the richness. A simple arugula salad with lemon vinaigrette is perfect.
- Roasted Broccoli: The slight bitterness of charred broccoli balances the sweet onions.
- Garlic Green Beans: Keeps the meal feeling classic and grounded.
- Steak: Serve this as a side dish alongside a nice seared steak for a “steakhouse at home” vibe.
- Since this dish is so rich, I usually skip a heavy dessert, but if you want a little something sweet, my Classic Chocolate Chip Cookies are always a winner.
Storing and Reheating Tips
- Fridge: Store leftovers in an airtight container for up to 3-4 days.
- Reheating: Add a splash of milk or broth before reheating in the microwave or on the stovetop to bring the creamy texture back.
- Freezer: You can freeze the baked dish for up to 2 months, but the bread topping might get a little soft upon thawing.
Nutrition Facts
| Nutrient | Amount per Serving |
|---|---|
| Calories | 580 kcal |
| Total Fat | 32g |
| Saturated Fat | 19g |
| Cholesterol | 95mg |
| Sodium | 820mg |
| Carbohydrates | 52g |
| Dietary Fiber | 3g |
| Sugars | 6g |
| Protein | 24g |
Nutrition information is estimated and may vary based on ingredients and cooking methods. Source: USDA FoodData Central.
FAQs About French Onion Soup Mac and Cheese
Can I make this without alcohol?
Yes! The sherry adds a nice acidity, but you can easily swap it for apple cider vinegar or just use a little extra beef broth to deglaze the pan.
Why is my sauce grainy?
Grainy sauce usually happens if the cheese was added while the sauce was boiling hot, or if you used pre-shredded cheese. Always remove the sauce from the heat before stirring in the cheese.
Can I use white onions instead of yellow?
You can, but yellow onions (or sweet onions) have a higher sugar content which makes them caramelize better and taste sweeter, which is key for that classic soup flavor.
Final Thoughts
This French Onion Soup Mac and Cheese is honestly a showstopper. It takes a little extra love to get those onions perfect, but I promise the first bite makes it all worth it. It’s savory, cheesy, and just feels special.
If you’re looking for more comforting pasta bakes to add to your rotation, don’t forget to check out my Million Dollar Spaghetti!
Pin this recipe and let me know in the comments how it turned out!
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French Onion Soup Mac and Cheese
Ingredients
Equipment
Method
- In a large skillet, melt 4 tablespoons of butter over medium heat. Add the sliced onions and a pinch of salt. Cook, stirring occasionally, for 30-45 minutes until the onions are soft, jammy, and deep golden brown. If they start to dry out, add a splash of water.
- Pour in the dry sherry (or beef broth) to deglaze the pan, scraping up any browned bits from the bottom. Stir in the fresh thyme and remove from heat.
- Preheat oven to 375°F (190°C). Grease a 9×13 inch baking dish.
- Boil the pasta in a large pot of salted water until al dente (about 1 minute less than package directions). Drain and set aside.
- In the same large pot, melt 4 tablespoons of butter over medium heat. Whisk in the flour and cook for 1-2 minutes until bubbly and golden.
- Slowly whisk in the beef broth and whole milk. Continue whisking constantly until the sauce simmers and thickens enough to coat the back of a spoon (about 3-5 minutes).
- Remove the pot from heat. Stir in the grated Gruyère and Mozzarella cheese until melted and smooth. Season with salt and pepper to taste.
- Add the cooked pasta and about 3/4 of the caramelized onions to the cheese sauce. Stir until well combined.
- Pour the mixture into the prepared baking dish. Top with the remaining caramelized onions.
- Toss the torn baguette pieces with 2 tablespoons of melted butter and scatter them over the top of the pasta.
- Bake for 20-25 minutes, or until the sauce is bubbly and the bread topping is golden brown and crispy. Let sit for 5 minutes before serving.