French Onion Soup Mac & Cheese

Name: French Onion Soup Mac & Cheese
Prep time: 15 min
Cook time: 40 min
Total time: 55 min
Cuisine: French
Ingredients: 3 large yellow onions, thinly sliced; 3 tbsp butter; 2 cloves garlic, minced; 1 tsp dried thyme; Salt and freshly ground black pepper, to taste; 3 tbsp all-purpose flour; 4 cups beef broth (or vegetable broth for vegetarian option); 1 cup half-and-half or heavy cream; 1 ½ cups grated Gruyère cheese; 1 cup sharp white cheddar cheese, grated; 12 oz elbow macaroni; Optional: French bread or baguette slices for toasting; Extra grated cheese for topping (about ½ cup)

by Joudia Elise

Published on: December 18, 2025

Delicious bowl of French Onion Soup Mac & Cheese topped with melted cheese and onions.

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Golden, bubbling, and heady with sweet caramelized onion and nutty Gruyère, this French Onion Soup Mac & Cheese hits every comforting note. The aroma of slowly browned onions and melted cheese fills the kitchen, while toasted baguette crumbs add a satisfying crunch on top. It’s a seasonal, sustainable twist on two classics—easy enough for a weeknight but impressive for cozy dinner parties. If you like savory mashups, try pairing it with a savory roast or check my take on French Onion Chicken for a full menu.

Table of Contents

Why You’ll Love This Recipe

This dish is ideal for chilly nights, holiday dinners, or when you want an indulgent comfort-food centerpiece that feels built from pantry staples. It combines the caramelized depth of French onion soup with the creamy, cheesy hug of mac & cheese, delivering complex flavor without complicated technique. Versatile and forgiving, you can make it vegetarian with vegetable broth, scale it up for a crowd, or prepare it ahead and finish under the broiler for a golden crust. Leftovers reheat beautifully, making it a winner for meal prep too.

Seasonal Ingredients Spotlight

This recipe shines in late autumn and winter when sweet yellow onions are at their best—firm, glossy, and fragrant. As they caramelize, their color deepens from pale gold to deep amber, and their scent shifts from sharp to almost molasses-like sweetness. Using seasonal, locally grown onions reduces food miles and supports farmers; substitute European-style Gruyère with an aged local cow’s milk cheese if you prefer. Fresh thyme adds an earthy, piney note and tiny flecks of green on a browned top look lovely against golden cheese. For a complementary starter, consider a squash-forward soup like Autumn Squash Soup to continue the seasonal theme.

What You’ll Need

3 large yellow onions, thinly sliced
3 tbsp butter
2 cloves garlic, minced
1 tsp dried thyme
Salt and freshly ground black pepper, to taste
3 tbsp all-purpose flour
4 cups beef broth (or vegetable broth for vegetarian option)
1 cup half-and-half or heavy cream
1 ½ cups grated Gruyère cheese
1 cup sharp white cheddar cheese, grated
12 oz elbow macaroni
Optional: French bread or baguette slices for toasting
Extra grated cheese for topping (about ½ cup)

Sensory notes: choose onions that smell bright and feel firm; butter should foam and smell nutty as it heats; Gruyère melts into a silky, slightly sweet blanket. Substitutions: use plant-based butter and a cashew cream + dairy-free cheeses for a vegan version (texture will be a bit different). For gluten-free, swap the flour for a cup-for-cup GF blend and use GF pasta.

How to Make This Recipe

Caramelize the Onions — Slowly cook thinly sliced yellow onions in butter over low heat for 30–40 minutes, stirring occasionally, until they turn golden brown and develop a rich, sweet flavor.
The onions should become soft, deeply colored, and fragrant; if they crisp, reduce heat and add a splash of water to deglaze. Patience here is rewarded with deep, sweet complexity.
Build the Roux and Broth — Sprinkle flour over the caramelized onions and stir well to coat. Gradually whisk in the beef or vegetable broth and half-and-half or heavy cream until smooth and thickened.
Whisk constantly to avoid lumps; the sauce should thicken to coat the back of a spoon. If too thick, thin with reserved pasta water.
Add Aromatics & Cheese — Add minced garlic and dried thyme, then melt in Gruyère and sharp white cheddar cheeses until creamy and combined. Season with salt and pepper to taste.
Stir until the cheeses form a glossy, velvety sauce. Taste for seasoning—cheese and broth vary so adjust salt accordingly.
Cook the Pasta — Boil elbow macaroni according to package instructions until al dente. Drain well, reserving a small amount of pasta water in case you need to loosen the sauce later.
Slightly undercooking pasta prevents it from going mushy when baked; the pasta will finish cooking in the oven and soak up sauce.
Combine & Bake — Mix the cooked macaroni into the cheese sauce, ensuring every piece is evenly coated with the luscious, velvety sauce.
Transfer the mac & cheese to an oven-safe dish. Top with extra grated cheese and toasted baguette slices if desired. Broil briefly until the top is bubbly and golden brown, mimicking the classic French onion soup crouton finish. Watch carefully to avoid burning.
Rest & Serve — Let the dish rest 5 minutes before serving so the sauce firms slightly and slices hold their shape.
Serve warm with crisp greens to cut the richness or ladle small portions as a decadent side.

Step Examples

Prepare the Base — Slice and slowly caramelize onions; they should be soft, translucent, and deeply browned with a sweet, savory aroma. Deglaze the pan as needed to capture fond for richer flavor.

Mix the Ingredients — Whisk flour into the onions, then add broth and cream gradually until the sauce is smooth and glossy; cheese should melt into a silky texture.

Shape or Cook — Combine pasta with sauce, transfer to a baking dish, and top with cheese and baguette slices. Bake until thoroughly heated and the topping is bubbling and browned.

Finish or Garnish — Broil briefly for a golden crust, then scatter fresh thyme or cracked black pepper. Add toasted baguette slices to mimic classic French onion croutons.

Serve and Enjoy — Plate warm, noting the contrast between the creamy interior and crisp, toasted topping. Encourage diners to savor the sweet onion notes and gooey cheese.

Essential Tools

You’ll need a heavy-bottomed skillet or Dutch oven for even caramelization, a whisk for the sauce, a large pot for boiling pasta, a colander, an oven-safe baking dish, and a sharp grater for cheese. Optional: a mandoline for evenly thin onion slices and a broiler-safe rack for toasting baguette rounds. If you use affiliate or local cookware, choose a pan that retains heat well—this helps build fond and deep flavor.

Meal Prep & Storage Tips

This dish makes excellent leftovers. Cool to room temperature, then store in airtight containers in the refrigerator for up to 3–4 days. Reheat gently in a 325°F oven, covered, until warmed through; add a splash of milk or reserved pasta water if the sauce seems tight. For longer storage, freeze in portioned, freezer-safe containers for up to 2 months; thaw overnight in the fridge before reheating. Toast or broil a fresh layer of cheese and baguette slices after reheating to restore crunch.

Perfect Pairings

Serve this mac & cheese with a crisp green salad dressed with lemon vinaigrette to cut richness, or alongside roasted root vegetables to keep the menu earthy and seasonal. For drinks, a light-bodied red like Pinot Noir complements the caramelized onions and Gruyère, while a bright, unoaked Chardonnay works if you prefer white. For dessert, a light palate cleanser—such as a tart fruit sorbet—balances the meal; for a homier finish, a homemade apple crisp echoes the warm, caramel notes. If you want an unexpected cool-sweet pairing, try the creamy texture of 2-Ingredient Cottage Cheese Ice Cream as a playful contrast.

Nutrition Facts

Calories: ~180 kcal
Fat: 8 g
Carbohydrates: 24 g
Protein: 3 g
Fiber: 1 g
Sugar: 14 g

(Estimated per small serving; values will vary with portion size and ingredient choices.)

Avoid These Common Pitfalls

Overcooking the onions too quickly will burn them and taste bitter; keep the heat low and stir often. Lumpy sauce is usually from adding cold liquid too fast—temper the broth and whisk constantly. Too-saucy or too-dry mac & cheese? Reserve pasta water to loosen the sauce; add liquid in tablespoons until you reach a silky consistency. Undercooking the pasta results in a chalky bite—boil to just shy of al dente since it will finish in the oven.

Examples

Dough Too Dry — Add a splash of milk until pliable. (For dough-based sides or toppings.)

Chocolate Coating Breaks — Ensure melted chocolate is smooth and warm. (Applies to custard-based desserts served after.)

Unevenly Shaped Balls — Use a cookie scoop. (For uniform portions like croquettes or fritters.)

Pro Tips for Best Results

Use low heat and patience when caramelizing onions; the color and aroma are your cue—deep amber and sweet-smelling. Grate cheese from a block for best melt and flavor; pre-shredded cheese often contains anti-caking agents that affect creaminess. Toast baguette slices under the broiler until just golden to mimic classic soup croutons; watch closely. If you’re short on time, caramelize onions ahead and refrigerate for up to 3 days to speed weeknight prep.

Recipe Variations to Explore

Vegetarian: Swap beef broth for a rich vegetable stock and add a splash of mushroom soy for umami.
Smoky Twist: Stir in a pinch of smoked paprika or use smoked cheddar in place of some Gruyère.
Protein Boost: Mix in shredded roast chicken or crispy pancetta for added texture and heft.
Lighter Version: Use half-and-half or a mix of milk + cornstarch for a lighter sauce and whole-wheat pasta for added fiber.
Gluten-Free: Use a GF flour for the roux and your favorite GF pasta shape.

Dietary Adaptations & Safety Info

Allergens: contains dairy and gluten (unless substituted). For vegan versions, use plant-based butter, a creamy cashew or oat-based milk, and dairy-free melty cheese alternatives. For gluten-free diners, substitute the flour with a GF blend and choose GF pasta. Always ensure reheated leftovers reach 165°F (74°C) for safety, and cool hot dishes before refrigerating to avoid bacterial growth.

Frequently Asked Questions

Q: Can I make this ahead of time?
A: Yes — caramelize the onions and make the cheese sauce up to 3 days ahead; refrigerate separately from cooked pasta. Reheat gently, combine, and broil to finish.

Q: Can I use other cheeses besides Gruyère?
A: Absolutely. Emmental, Comté, or aged Cheddar work well. Mix a melting cheese with a sharp option for depth.

Q: How do I prevent the top from burning under the broiler?
A: Broil on the upper rack for short bursts (1–2 minutes), watching constantly. Pull it the moment the cheese bubbles and turns golden.

Q: Is there a vegetarian version?
A: Yes — simply use vegetable broth instead of beef broth and follow the same method. Consider adding mushrooms for added umami.

Q: What pasta shapes work best?
A: Elbow macaroni is classic, but shells, cavatappi, or small rigatoni hold sauce beautifully. Use shapes with nooks to trap the cheesy sauce.

Q: Can I freeze leftovers?
A: Yes; portion into freezer-safe containers and freeze up to 2 months. Thaw overnight in the fridge before reheating in the oven.

Q: My sauce is grainy — what went wrong?
A: Likely overheated cheese or not enough liquid. Remove from heat and whisk in a bit of warm milk or reserved pasta water to smooth it out.

Final Thoughts & Next Steps

This French Onion Soup Mac & Cheese is a cozy, show-stopping hybrid that rewards patience with deep, savory layers. Try it for your next gathering or make it as a comforting solo supper—either way, you’ll have a comforting, crowd-pleasing dish. If you make it, leave a note in the comments and tag your photos so others can try it too.

Conclusion

For another take on this comforting mash-up, see Eitan Bernath’s French Onion Mac and Cheese.

Author

Joudia Elise
I'm a recipe developer and wellness enthusiast at We Cook Recipe, where I share practical, family-friendly recipes that support real life not restrictive diets. My approach combines traditional cooking wisdom with modern nutritional understanding, always prioritizing sustainable habits over quick fixes. When I'm not in the kitchen, you'll find me testing wellness trends (like this one!) to separate fact from hype for our community.

Cheesy Recipes comfort food French Onion Soup Mac and Cheese Savory Dishes