French Onion Pasta (One Pot, Cheesy and Broiled)

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If you love French onion soup, this pasta is for you. It has the same deep, sweet caramelized onions, the same savory beef broth and the same bubbling layer of Gruyère on top.

The difference is that the pasta cooks right in that onion broth, soaking up flavor as it goes. You end up with a creamy, glossy sauce that clings to every piece, all from one pot.

The onions take patience, but they don’t need constant attention. Once they’re done, dinner comes together in about 20 minutes.

Why this recipe works

• Truly caramelized onions. Cooking the onions low and slow for 45 minutes or more builds the rich, jammy flavor that defines French onion anything.
• Pasta cooked in broth. The pasta absorbs beef broth instead of plain water, and its starch thickens the sauce naturally.
• A little flour. One tablespoon of flour gives the sauce a silky body so it doesn’t turn soupy.
• A broiled cheese top. Finishing under the broiler creates the browned, stretchy Gruyère crust you’d get on a bowl of soup.
• One pot. Everything happens in a single broiler-safe pot, which means fewer dishes.

Ingredients you’ll need

The exact amounts are in the recipe card. Here is what to know about the main players.

• Yellow onions. Yellow onions have the best balance of sweetness and sharpness for caramelizing. Sweet onions work but can taste a little flat. Three pounds looks like a mountain, but they cook down to about 1 1/2 cups.
• Butter. Butter adds flavor and helps the onions brown. A splash of olive oil with it keeps the butter from scorching.
• Dry white wine or sherry. Used to scrape up the browned bits in the pot. Dry sherry gives a more classic French onion soup flavor. For an alcohol-free version, use extra broth plus 1 teaspoon of balsamic vinegar.
• Beef broth. Use a good low-sodium beef broth so you can control the salt. Mushroom or vegetable broth works for a vegetarian version, though the flavor will be lighter.
• Short pasta. Cavatappi, rigatoni, or medium shells all hold the sauce and onions well. Avoid very thin pasta, which overcooks before the broth reduces.
• Gruyère. Nutty, melty Gruyère is traditional. Swiss, fontina or a mix with mozzarella also work. Parmesan adds a salty finish.
• Fresh thyme and Worcestershire. Thyme is the classic French onion herb, and Worcestershire sauce adds savory depth.

Ingredient notes and smart substitutions

Onions

Buy firm yellow onions with tight, papery skins and no soft spots. Three pounds is about four large onions, and they should all be sliced to the same 1/8-inch thickness so they caramelize at the same pace.

Sweet onions like Vidalia can be swapped 1:1, but they have more water and less bite, so the finished pasta tastes a little one-note. Red onions work in a pinch but turn a muddy gray-brown. Avoid pre-sliced bagged onions; they are usually cut too thick and dry out on the edges before they soften.

Butter and oil

The recipe uses 4 tablespoons of unsalted butter plus 1 tablespoon of olive oil. If you only have salted butter, use it and cut the added salt to 1/2 teaspoon. For a dairy-free base, use 5 tablespoons of olive oil total; you lose a little richness but the onions still caramelize well.

Wine or sherry

Dry sherry gives the most soup-like flavor, and dry white wine gives a cleaner, brighter version. Cooking sherry from the vinegar aisle is heavily salted, so if that is all you have, use it and skip the added salt entirely. To replace the 1/2 cup of wine, use 1/2 cup broth plus 1 teaspoon balsamic vinegar or 1 teaspoon sherry vinegar.

Beef broth

Low-sodium boxed broth works well, and 4 cups of it plus 1 cup water is the right amount for 12 ounces of pasta. Bouillon paste dissolved in water is a fine substitute; use it at the strength on the label and add no salt until the end. For vegetarian, use 4 cups mushroom broth and add 1 extra teaspoon of Worcestershire (vegetarian style) or 1 teaspoon soy sauce to make up for the lost depth.

Pasta

Any short shape that takes 10 to 12 minutes to cook in water will work here. Bronze-cut pasta with a rough surface holds the sauce better than glossy pasta. Whole wheat pasta needs about 1/2 cup more water and 2 to 3 extra minutes. Gluten-free pasta releases less starch, so add 1 extra teaspoon of flour with the garlic to keep the sauce from turning thin.

Gruyère

Look for a wedge aged 6 months or more; it melts smoothly and has the nutty flavor you want. Comté and Emmental are the closest swaps, ounce for ounce. Fontina melts beautifully but is milder, so pair it with a little extra Parmesan. Skip pre-shredded blends, which are coated in starch and turn gritty under the broiler.

Flour

One tablespoon of all-purpose flour is enough to give the sauce body. Use 1 1/2 teaspoons of cornstarch stirred into the cold broth instead if you want to keep the dish gluten-free with gluten-free pasta.

How to make it

1. Caramelize the onions

Slice the onions thinly from root to tip so the pieces hold their shape. Melt the butter with the oil in a large broiler-safe Dutch oven, add the onions and a teaspoon of salt, and stir to coat.

Cook over medium heat for the first 10 minutes, stirring occasionally, until they soften and release their liquid. Then lower the heat to medium-low and keep cooking, stirring every few minutes, for another 35 to 50 minutes. They’re done when they are soft, jammy and deep golden brown.

If the bottom of the pot starts to look dark, add a tablespoon of water and scrape. That browned layer is flavor, and a little water keeps it from burning.

2. Build the broth

Stir in the garlic and flour and cook for a minute. Pour in the wine or sherry and scrape the bottom of the pot, then let it bubble until mostly evaporated. Add the beef broth, water, Worcestershire and thyme and bring it all to a boil.

3. Cook the pasta in the pot

Add the pasta, stir, and simmer uncovered over medium heat, stirring every couple of minutes so it doesn’t stick. In 12 to 15 minutes, the pasta should be al dente and the liquid reduced to a glossy sauce. If it gets too dry before the pasta is tender, add water a quarter cup at a time.

4. Add cheese and broil

Take the pot off the heat and stir in part of the Gruyère and the Parmesan until melted. Scatter the rest of the Gruyère over the top and slide the pot under the broiler for 2 to 4 minutes, watching closely, until the cheese is bubbling and browned in spots.

Common mistakes and how to fix them

The onions browned but never turned jammy. This happens when the heat is too high. The edges brown before the centers soften, and the onions taste sharp. Turn the heat down to medium-low, add 2 tablespoons of water, cover the pot for 5 minutes to steam them soft, then uncover and keep cooking.

The bottom of the pot turned black. The sugars in the onions scorch when the pot runs dry. Add a tablespoon of water as soon as the fond turns dark brown, scrape it up and stir it into the onions. If the layer is already black and bitter, transfer the onions to another pot and leave the burned layer behind.

The pasta stuck together or to the bottom. Pasta cooked in a small amount of liquid needs frequent stirring for the first 5 minutes, when it releases the most starch. Stir every 2 minutes, and make sure the liquid is at a steady simmer, not a bare bubble.

The pasta is done but the sauce is soupy. Either the lid was on or the heat was too low for evaporation. Turn the heat up to medium-high and simmer uncovered for 2 to 3 more minutes, stirring, before adding the cheese. The Gruyère will also thicken it.

The sauce is thick and dry before the pasta is tender. Different pasta shapes absorb liquid at different rates. Add hot water 1/4 cup at a time and keep simmering. Do not add more broth at this stage or the dish will end up too salty.

The cheese turned greasy or stringy. Gruyère breaks when it is boiled. Take the pot fully off the heat before stirring in the first cup of cheese, and keep the broiler time under 4 minutes.

The top burned before it bubbled. The rack was too close. Move it to 6 inches from the element, and if your broiler runs hot, leave the oven door cracked and check every 60 seconds.

Timing and make-ahead plan

1. Up to 5 days ahead: Caramelize the onions completely, cool and refrigerate them in a covered container. Or freeze them flat in a zip-top bag for up to 3 months.
2. Morning of: Shred the Gruyère and Parmesan, mince the garlic and strip the thyme. Keep the cheese covered in the fridge.
3. 30 minutes before dinner: Warm the onions in the pot over medium heat until they sizzle again, about 3 minutes. Add the garlic and flour and continue with the recipe from there.
4. 10 minutes before: Move the oven rack and heat the broiler while the pasta finishes.
5. Holding it warm: Stop before adding the cheese. Cover the pot and hold it over the lowest heat for up to 20 minutes, then stir in 1/2 cup hot broth to loosen, add the cheese and broil right before serving.

Tips for the best French onion pasta

• Don’t rush the onions. Turning up the heat will brown them faster on the outside but leave them sharp and sometimes bitter. Low and slow is the whole point.
• Use a wide pot. More surface area means the onions caramelize more evenly and faster.
• Make the onions ahead. Caramelized onions keep in the fridge for up to 5 days, which makes this a 25-minute weeknight dinner.
• Check the broiler distance. Put the rack about 6 inches from the heat. Closer than that and the cheese can burn before it melts.
• Salt at the end. Broth, Parmesan and Gruyère all add salt, so taste before adding more.
• Keep stirring the pasta. Pasta cooked in a small amount of liquid releases a lot of starch and can stick to the bottom. Stirring every couple of minutes keeps it loose and helps the sauce turn creamy.
• Serve right away. The sauce keeps thickening as it sits. If it tightens up before everyone is at the table, stir in a splash of hot broth or water before broiling.

Variations

• Add chicken. Stir in 2 cups of shredded rotisserie chicken with the cheese.
• Mushroom French onion pasta. Brown 8 ounces of sliced cremini mushrooms after the onions caramelize. If you like that direction, you may also enjoy our creamy mushroom stroganoff.
• Creamier version. Stir in 1/2 cup of heavy cream with the cheese for a richer, more sauce-like finish.
• Crunchy topping. Sprinkle 1/2 cup of buttered panko over the cheese before broiling for a crouton-like crunch.
• Vegetarian. Use a rich mushroom broth and a vegetarian Worcestershire sauce.

Equipment that makes this easier

• A 5- to 6-quart wide Dutch oven. The wide base gives 3 pounds of onions room to brown instead of steam, and enameled cast iron is safe under the broiler if the lid knob is removed.
• A sharp chef’s knife or mandoline. Even 1/8-inch slices caramelize at the same rate; uneven slices give you burnt shreds mixed with raw ones.
• A flat-edged wooden spoon. The flat edge scrapes the fond off the bottom of the pot far better than a rounded spoon.
• A box grater. Freshly shredded Gruyère melts into the sauce without the starch coating on bagged cheese.
• A silicone handle cover or dry towel. The pot handle will be very hot after the broiler, and a damp towel conducts heat straight to your hand.

Scaling up or down

To halve it: Use 1 1/2 pounds onions, 6 ounces pasta, 2 cups broth and 1/2 cup water in a 3-quart pot or 10-inch oven-safe skillet. A smaller batch of onions caramelizes faster, so start checking at 30 minutes. Keep the flour at 2 teaspoons rather than a rounded 1/2 tablespoon so the sauce still has body.

To double it: Six pounds of onions will not caramelize properly in one pot; they pile too deep and steam. Split them between two wide pots, or cook them in two batches on different days and freeze the first. Cook the pasta in a 7- to 8-quart pot with 8 cups broth and 2 cups water, and expect the pasta to take 3 to 5 minutes longer since the liquid takes longer to reduce.

What to serve with it

This pasta is rich and savory, so pair it with something fresh. A green salad with Dijon vinaigrette, roasted broccoli or lemony green beans all work well. Our fall side dishes list has more options.

If you’re planning a pasta-heavy week, it makes a nice change of pace alongside marry me chicken pasta and lentil Bolognese.

How to store, freeze and reheat

Refrigerate: Store leftovers in an airtight container for up to 4 days. The pasta will absorb more sauce as it sits.

Reheat: Warm individual portions in a skillet or the microwave with a splash of broth or water to loosen the sauce. Stir halfway through.

Freeze: Finished pasta dishes with melted cheese tend to turn grainy and soft when frozen, so this one is best fresh. The caramelized onions, though, freeze very well for up to 3 months. Make a double batch and freeze half in a zip-top bag for a head start next time.

Leftover ideas

• French onion pasta bake. Spread leftovers in a buttered baking dish, add a splash of broth, top with more Gruyère and bake at 375°F until hot in the center, about 20 minutes.
• Crispy pasta cakes. Press cold pasta into 1/2-inch-thick patties, dust with flour and pan-fry in butter until golden on both sides. Serve with a fried egg.
• Stuffed peppers. Fill halved bell peppers with leftover pasta, top with cheese and bake at 375°F for 25 minutes.
• French onion soup shortcut. Simmer a cup of leftovers with 2 cups beef broth, ladle into oven-safe bowls, top with a slice of toast and cheese and broil.

Nutrition notes

One serving (a quarter of the recipe) lands at roughly 650 to 750 calories, 28 to 32 grams of protein, 70 to 80 grams of carbohydrates and 28 to 34 grams of fat. Most of the fat comes from the butter and Gruyère. These are estimates only; actual numbers vary with your pasta brand, cheese and portion size.

• Lighter: Cut the butter to 2 tablespoons and use 4 ounces of Gruyère instead of 6. The onions still caramelize, and the top still browns.
• More protein: Stir in 2 cups shredded chicken or 1 cup cooked white beans with the cheese.
• Gluten-free: Use gluten-free short pasta, swap the flour for 1 1/2 teaspoons cornstarch and check that your Worcestershire is gluten-free.
• Dairy-free: Caramelize the onions in olive oil and finish with a plant-based shredded cheese that melts, plus 2 tablespoons nutritional yeast for the nutty note. The top will not brown as deeply.

Frequently asked questions

How long does it take to caramelize onions?

Plan on 45 minutes to an hour for 3 pounds of onions over medium to medium-low heat. Recipes that promise caramelized onions in 10 minutes are usually just browning them.

What is the best cheese for French onion pasta?

Gruyère is the classic choice because it is nutty and melts smoothly. Swiss, fontina or a mix of Gruyère and mozzarella also work well.

Can I make French onion pasta without wine?

Yes. Replace the wine with extra beef broth and add 1 teaspoon of balsamic vinegar for a little acidity.

What pasta shape works best?

Short, sturdy shapes with ridges or curves, like cavatappi, rigatoni or medium shells, hold the onions and sauce best and stand up to cooking in broth.