If you adore the comforting flavors of French onion soup and crave the indulgence of creamy mac and cheese, this French Onion Mac and Cheese is the perfect union of both. With slowly caramelized sweet onions delivering rich, deep notes and a luxurious gruyere cheese sauce enveloping tender pasta, it’s a baked side dish that feels both gourmet and homey.
This dish takes a bit of time to prepare, but the layering of flavors and textures – from bubbling cheese to crispy breadcrumb topping and fragrant thyme – makes every minute worthwhile. It’s a show-stopping addition to dinner tables or holiday spreads where you want something both familiar and unexpectedly delicious.
- Deep caramelized onions provide sweet and savory richness infusing every bite.
- A velvety gruyere cheese sauce offers a nutty, creamy elevation to classic mac and cheese.
- Baked with a crisp seasoned breadcrumb topping for textural contrast and visual appeal.
- Perfectly portioned to serve a crowd with elegant yet approachable flavors.
Ingredients
- Olive Oil: Provides a subtle fruity base for sautéing and caramelizing the onions beautifully.
- Sweet Onions: Thinly sliced for slow caramelization, bringing out deep, natural sweetness and complexity.
- Kosher Salt and Pepper: Essential for seasoning the onions and balancing the rich cheese sauce flavors.
- Short Cut Pasta: Cooked al dente for perfect bite and to hold creamy sauce without becoming mushy.
- Unsalted Butter: Creates a silky roux base for thickening the cheese sauce while adding richness.
- All-Purpose Flour: Combines with butter to form the roux, ensuring a smooth, velvety sauce texture.
- Milk: Slowly incorporated to create a creamy, luscious cheese sauce without lumps.
- Freshly Ground Nutmeg: Adds subtle warmth and depth, enhancing the cheese flavors harmoniously.
- Gruyere Cheese: Freshly grated for smooth melting and a slightly sweet, nutty profile.
- Parmesan Cheese: Adds sharp, salty notes that intensify the overall flavor character.
- Seasoned Bread Crumbs: Provide a golden, crispy topping that contrasts beautifully with the creamy pasta.
- Fresh Thyme: Sprinkled on top for an herbal, aromatic finish that lifts the dish.
Instructions
- Caramelize the Onions Slowly
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Heat olive oil in a large oven-safe skillet and add thinly sliced sweet onions with a pinch of kosher salt. Cook over medium heat, stirring often until they soften, then reduce to low or medium-low and continue cooking, stirring frequently for 60 to 90 minutes. This slow cooking process draws out their natural sugars, resulting in deeply golden, caramelized onions full of rich flavor without bitterness.
- Preheat Oven and Cook Pasta
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While the onions caramelize, preheat the oven to 375°F. Boil your short cut pasta according to package directions until just al dente, then drain well and set aside. Cooking pasta to this texture ensures it absorbs the cheese sauce perfectly without becoming mushy after baking.
- Create a Smooth Roux
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Once onions are caramelized and set aside, add the butter to the same skillet. After it melts, whisk in the flour to form a roux and cook for 2 to 3 minutes until golden and nutty-smelling. This step removes the raw flour taste and thickens the sauce smoothly.
- Make the Cheese Sauce
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Slowly pour in milk while whisking constantly to prevent lumps, letting the sauce thicken. Add freshly grated nutmeg for warmth and stir in most of the grated gruyere and parmesan cheeses until melted. This creates a luscious, creamy base that will cling beautifully to your pasta.
- Combine Pasta with Cheese and Onions
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Fold three-quarters of the caramelized onions into the cheese sauce, then add the cooked pasta. Toss gently over low heat until all ingredients are fully combined, ensuring every bite is infused with the sweet onion and cheesy goodness.
- Top and Bake
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Transfer mixture evenly in the skillet or a baking dish if needed. Sprinkle the reserved cheeses and remaining caramelized onions on top, then add an even layer of seasoned bread crumbs. Bake for 25 to 30 minutes until the top is golden brown and the sauce is bubbly, creating a wonderful contrast of textures.
- Finish with Fresh Thyme and Serve
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Remove from oven and sprinkle with fresh thyme leaves for bright herbal notes. Let cool slightly before serving to allow flavors to meld and the sauce to thicken just enough for the perfect creamy bite.
- Caramelizing onions requires patience but significantly enhances the flavor and sweetness of this dish.
- Use freshly grated cheeses for optimal melting and fresh flavor, not pre-shredded, which often contain anti-caking agents.
- Seasoned bread crumbs add a crucial crunch and seasoned note; plain bread crumbs can be enhanced with your own herbs and spices.
Storage Tips
Store any leftovers in an airtight container in the refrigerator for up to 3 days. Reheat gently in the oven or microwave to maintain creaminess and avoid drying out the pasta.
Serving Suggestions
This dish pairs wonderfully with a crisp green salad or roasted vegetables to balance the richness. It can also serve as a hearty stand-alone meal or a decadent side for grilled meats or poultry.
- For faster caramelization, add a small amount of sugar or honey, but stir frequently to avoid burning.
- Cook pasta just shy of al dente since it will continue to cook in the oven, preventing a mushy texture.
- Fresh thyme adds aroma and a slight earthiness; feel free to experiment with rosemary or sage for variation.
FAQs
- Can I use different cheese instead of gruyere?
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Yes, swiss or fontina make excellent substitutes with similar meltability and flavor profiles.
- How can I speed up caramelizing onions?
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Add a teaspoon of sugar or honey to the onions early on and increase the heat slightly, but watch closely to prevent burning.
- Is this recipe freezer-friendly?
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While possible, baked mac and cheese is best fresh. To freeze, cool completely, freeze in airtight containers, and reheat slowly in the oven.
- Can I make this gluten-free?
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Use gluten-free pasta and substitute the all-purpose flour with a gluten-free flour blend or cornstarch for the roux.
- What pasta shape works best?
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Short cut pasta like elbow macaroni or cavatappi works well to hold the sauce and provide bite.
- Can I prepare parts of the recipe ahead of time?
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Yes, you can caramelize onions and cook pasta up to a day before and assemble just before baking.
- What if I don’t have an oven-safe skillet?
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Combine ingredients in the skillet then transfer to a buttered baking dish before topping and baking.
French Onion Mac Cheese
Equipment
- 1 large oven-safe skillet
- 1 oven
- 1 pot for boiling pasta
- 1 whisk
Ingredients
- 3 tablespoons olive oil
- 4 large sweet onions thinly sliced
- Kosher salt and pepper to taste
- 1 pound short cut pasta cooked
- 3 tablespoons unsalted butter
- 1/4 cup all-purpose flour
- 2 1/2 cups milk
- 1/4 teaspoon freshly ground nutmeg
- 12 ounces Gruyere cheese freshly grated
- 4 ounces Parmesan cheese freshly grated
- 1/3 cup seasoned bread crumbs
- Fresh thyme for garnish
Instructions
- Heat olive oil in a large oven-safe skillet over medium heat and stir in thinly sliced onions with a pinch of salt.
- Cook onions, stirring frequently, until softened, about 10 to 15 minutes.
- Reduce heat to low or medium-low and cook onions, stirring often, for 60 to 90 minutes until golden and caramelized, adding water if needed to prevent burning.
- Preheat oven to 375°F (190°C) and boil pasta according to package instructions; drain and set aside.
- Transfer caramelized onions to a plate to cool; optionally add sugar or syrup during caramelization to speed process if needed.
- In the same skillet, melt butter and whisk in flour to form a roux; cook for 2 to 3 minutes until golden and nutty.
- Gradually whisk in milk, stirring constantly until mixture thickens; add nutmeg.
- Stir in most of the grated Gruyere and Parmesan cheese until melted.
- Add three-quarters of the caramelized onions and cooked pasta to the cheese sauce; mix until well combined.
- Top with remaining cheese and caramelized onions; sprinkle with seasoned bread crumbs.
- Bake in preheated oven for 25 to 30 minutes until golden and bubbly.
- Remove from oven, garnish with fresh thyme, and serve warm.
Notes
- To speed caramelization, add a teaspoon of sugar or honey while cooking onions.
- Store leftovers covered in refrigerator up to 3 days.
- Reheat in oven for best texture.
