This French Onion Mac and Cheese is the ultimate mashup of two comfort food favorites: mac and cheese and French onion soup!
It’s creamy and cheesy, and packed with deeply caramelized onions for amazing depth, then finished with a golden panko breadcrumb topping for the perfect crunch. Like my French Onion Pot Roast, this French onion mac and cheese is always a winner!
Everyone always goes crazy for this baked French onion mac and cheese! Serve it for the holidays or at your next family gathering, and watch how quickly it disappears!
What makes this French onion mac and cheese special is the combination of savory Gruyere cheese – which has an amazing, complex sharp flavor – and those signature French onion flavors. Together, they elevate the classic mac and cheese recipes, such as this stovetop mac and cheese or my white cheddar mac and cheese into something incredible.
I want to mention how important it is to not rush caramelizing the onions. Pack your patience because cooking them low and slow is the best way to bring out their rich color, deep flavors and sweetness. You can even do this part ahead!
If you’re lucky enough to have leftovers, I highly recommend making my Mac and Cheese Bites!
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Why I Love This Recipe
- Cozy and comforting. It’s two classic comfort dishes in one baked, cheesy dish!
- Perfect for the holidays or gatherings. This French onion mac and cheese recipe makes a big batch.
- Easy to make. Even easier when you caramelize onions ahead, plus it’s freezer-friendly.
Ingredient Notes
I have included a few notes from recipe testing that I hope you find helpful. Possible substitutions are provided here as well.
- Yellow onions: They have a mild, slightly sweet flavor, perfect for caramelizing. Once caramelized, they will develop a deep flavor without being overpowering. Onions reduce a lot, so plan to use about 4 large onions!
- Unsalted butter, balsamic vinegar, and thyme for the onions: Cooking the onions in butter is extra flavorful. The vinegar gives them a nice color and extra flavor, and helps tenderize them better.
- Cavatappi pasta: This is my favorite pasta for French onion mac and cheese! They are just the right size, and their shape allows for the creamy sauce and caramelize onions to cling onto.
- Unsalted butter, all-purpose flour, and whole milk: This is the base of the cheese sauce that helps to thicken it up and be creamy. Use whole milk for the extra richness.
- Gruyere cheese: Gruyere is what’s traditionally used in French onion soup, so that’s what we’re going for here. IMPORTANT: Use freshly grated cheese so it melts into a smooth sauce! Pre-shredded cheese can sometimes contain extra ingredients that make it gritty.
- Dijon mustard, garlic powder, salt and pepper for seasoning
- Panko breadcrumbs, tossed with olive oil (for crispiness and color)
As always, ingredient quantities are listed in the recipe card down below.
How to Make French Onion Mac and Cheese
Prepping for this delicious French Onion mac and cheese is actually really easy! All you need is a little patience for the onions to caramelize. Let’s make it!
Step 1 | Caramelize onions
Melt butter in a large 12-inch skillet. Add the sliced onions and a pinch of salt, and cook for 15 minutes over medium heat. Reduce heat to medium-low, then continue cooking for another 30 minutes, stirring only occasionally, until the onions are caramelized. In the last 5 minutes, stir in the remaining butter, balsamic vinegar, and thyme.
Step 2 | Start the mac and cheese sauce
Cook the pasta: About 20 minutes before the onions are ready, cook the pasta to al dente. Drain, rinse, and set aside.
Make the sauce: Melt butter in a pot over medium heat. Whisk in flour and cook for a few minutes until nutty. Gradually whisk in milk until smooth and thickened, it will thicken as it heats up. Season with Dijon, garlic powder, salt, and pepper.
Step 3 | Add cheese and pasta
Reduce heat to low, then stir in the shredded gruyere cheese until melted and smooth. Then, add the cooked pasta until evenly coated.
Make sure the Gruyere cheese is freshly grated! Use a box grater or food processor (with the shredding blade).
Step 4 | Assemble and bake
In a 9×13-inch baking dish, layer half of the mac and cheese. Swirl in most of the caramelized onions and sprinkle with more cheese. Add the remaining mac and cheese, then top with the rest of the onions, remaining cheese, and panko tossed with a bit of olive oil. Bake, uncovered, at 375 degrees F for 25 minutes until golden brown and bubbly.
Let the baked French onion mac and cheese cool slightly before serving.
Tips for Success
- Use about 4 large onions. It may seem like a lot, but they will reduce significantly. They should be thinly sliced to about the same size.
- Use yellow onions. They are milder and sweeter.
- Use the right pan for the onions. I use a 12-inch deep pan. This allows for the onions spread out, without overcrowding and steaming.
- Patience is key. Take care to caramelize slowly, and only stir occasionally. They take about 40-45 minutes.
- Cook pasta until just al dente since it will all finish baking in the oven.
- Grate your own cheese! Pre-shredded cheese often comes with added starch, which can make the sauce gritty.
- Low heat for the cheese. When adding the cheese into the sauce, do it over very low heat or even off the heat.
Make Ahead, Storage, Freezing
Caramelize onions ahead: Caramelize onions up to 2 days ahead, and keep refrigerated. Warm it up slightly before assembling your French onion mac and cheese.
Make ahead, bake later: Assemble the mac and cheese in the casserole dish without the panko topping. Cover and refrigerate overnight. Before baking, let it sit at room temperature for 30 minutes, then add the topping and bake as directed, adding a few extra minutes until golden and bubbly.
Freezing: Once completely cooled, divide it up into freezer-safe containers. Freeze for up to 2 months. Thaw in the fridge overnight, then reheat smaller portions in the microwave, or larger portions in the oven until warmed through.
Storage: To store leftovers, keep it covered in an airtight container for up to 3-4 days. Reheat in the microwave oven or in the oven.
Recipe FAQs
Unfortunately, no. Caramelizing properly takes about 40-45 minutes. Turning up the heat can burn them and make them bitter. However, you can do this up to 2 days ahead and add them when assembling.
Gruyere cheese is ideal. You could also try white cheddar cheese, gouda, or Swiss cheese.
Certainly! Shells, fusilli, rigatoni, bowtie, or shells are great choices.
Yes, absolutely. I like the added texture it provides, but you can definitely omit.
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French Onion Mac and Cheese
Equipment
- Dutch oven deep skillet for the onions
Ingredients
Caramelized onions:
- 4 tablespoons unsalted butter - divided
- 4 large yellow onions - peeled and sliced
- 2 tablespoons balsamic vinegar
- 2 teaspoons fresh thyme leaves
- A splash of beef broth – or water - only if needed
For the mac and cheese:
- 1 pound cavatappi pasta
- ½ cup unsalted butter
- ⅓ cup all-purpose flour
- 4 cups whole milk – plus more as needed
- 16 ounces freshly shredded Gruyere cheese - divided (about 4 cups)
- 1 teaspoon dijon mustard
- 1 teaspoon garlic powder - or to taste
- Salt and pepper - to taste
Panko breadcrumb topping
- ⅓ cup panko breadcrumbs
- 3 tablespoons olive oil
Instructions
Caramelize onions
- In a large deep pan, melt 2 tablespoons of the butter over medium heat. Add the sliced onions and a pinch of salt. Cook over medium heat for 15 minutes to get a head start.
- Then, lower to medium-low heat, and continue cooking the onions, stirring only occasionally, until they are caramelized deep golden, another 30 minutes. In total, caramelizing onions takes 40-45 minutes. Note: The moisture from the onions will deglaze any brown bits, but if needed, add just a little splash of broth or wine to deglaze.
- During the last 5 minutes, add the remaining 2 tablespoons butter, balsamic vinegar, and thyme leaves until deglazed and golden. Set aside.
Make the mac and cheese
- Preheat oven to 375 degrees F. Note: You can start making the mac and cheese about 25 minutes before the onions are ready.
- Cook the pasta according to package directions until just al dente. Don’t overcook, as it will finish cooking in the oven. Drain and rinse with cold water to stop the cooking process. Set aside.
- In a large pot, melt ½ cup butter over medium heat. Whisk in the flour and cook for 2-3 minutes to form a roux. It should begin to smell nutty.
- Gradually stir in the milk, breaking up any lumps. It will thicken as it heats up. Season with dijon mustard, garlic powder, salt and pepper to taste.
- Over low heat, stir in 3 cups of Gruyere cheese until just melted. Turn off the heat, and continue stirring until the cheese sauce is smooth. Then, add the cooked pasta into the cheese sauce, stirring to coat evenly.
Assemble and bake
- Breadcrumb topping: Toss the panko breadcrumbs with olive oil. Set aside.
- Transfer half of the mac and cheese into a 9×13 baking dish. Swirl in most of the caramelized onions and most of the remaining 1 cup of shredded cheese. Save some onions and cheese for the topping.
- Layer on the remaining mac and cheese on top. Sprinkle the saved onions, cheese and the prepared panko mixture.
- Place the mac and cheese over a large sheet pan to catch any spills, just in case. Bake uncovered in the preheated 375 F degree oven for 23-25 minutes or until bubbly and melted. Let it cool slightly before serving. Enjoy!
Notes
- Cook pasta until just al dente since it will all finish baking in the oven.
- You need about 4 large onions. It may seem like a lot, but they will reduce significantly.
- Yellow onions are best because they are milder and sweet, perfect for caramelizing. Don’t use red onions.
- Use a large 12-inch deep pan for the onions. That way, they have room to cook without overcrowding, which can cause them to steam instead.
- Patience is key! They need about 40-45 minutes to properly caramelize.
Grate your own cheese! This is important. Pre-shredded cheese often comes with added starches that can make the sauce gritty.
- Caramelize onions up to 2 days ahead. Refrigerate and warm slightly before using.
- Or assemble, then bake later: Assemble (without the panko topping) the night before. Before baking, let sit on the counter for 30 minutes so it’s not so cold. Top with breadcrumbs, then bake as directed, adding a few extra minutes until bubbly.
- Freezing: Let cool completely, then freeze in portions for up to 2 months. Thaw in the fridge overnight and reheat.
- To reheat, add a splash of milk to make it creamy again.
- Cheese: Gruyere is best, but Swiss, gouda, or white cheddar work too.
- Pasta: Shells, fusilli, or rigatoni.
Tania says
I love this delicious and fun twist in this mac and cheese. The flavor is amazing. I’m going to make it again for Thanksgiving! It makes a big batch for everyone!