Active Time:

1 hr 40 mins

Total Time:

1 hr 40 mins

Yield:

4 servings

The jammy, sweet caramelized onions in this recipe — combined with an umami-packed mixture of broth, Worcestershire sauce, fish sauce, Parmesan and cheese — make this French onion pasta unforgettable. The sauce, based on classic French onion soup, has body and richness, while still being light enough to delicately coat the al dente bucatini. Fresh thyme and bay leaf infuse in some herbaceous depth while a sprinkling of buttery, toasted breadcrumbs add wonderful crunchy contrast to every bite. If you don't have bucatini on hand, use any long noodle

French Onion Bucatini — Jennifer Causey / Food Styling by Margaret Monroe Dickey / Prop Styling by Claire Spollen

Frequently asked questions

What does French onion taste like?

French onion soup is a classic soup featuring caramelized onions, beef broth, and a crouton topped with melted Gruyère, giving it a balance of salty, sweet, and savory flavors.

What is bucatini?

Bucatini is a thick long noodle with a hollow center that captures the sauce as it cooks. It is especially popular in Rome and the Lazio region of Italy.

Notes from the Food & Wine Test Kitchen

When caramelizing the onions, be sure to scrape the bottom of the pot when stirring occasionally to loosen the browned bits; this keeps them from burning and helps reincorporate them back into the onion mixture. The Gruyère has a tendency to clump if added to the pasta all at once. Do not use pre-grated cheese — it won’t melt well into the sauce. Be sure to remove the pot from the heat when you are ready to incorporate it, and add it very gradually, stirring constantly. The residual heat will be enough to gently melt the cheese. Wait to add the cheese to the breadcrumb mixture until you are ready to serve, otherwise the moisture of the cheese can soften the crispy breadcrumbs.

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Ingredients

Pasta

4 tablespoons unsalted butter
2 tablespoons neutral cooking oil (such as canola oil)
4 large (12 ounces each) red onions, thinly sliced (about 10 cups)
2 teaspoons kosher salt, divided
1/4 cup dry sherry
1 tablespoon all-purpose flour
2 cups unsalted beef or chicken broth
2 tablespoons Worcestershire sauce
1 teaspoon fish sauce
3/4 teaspoon black pepper
4 (5-inch) thyme sprigs
1 (2 1/2-inch) fresh or dried bay leaf
1/2 cup Parmigiano-reggiano cheese, grated (about 1/2 cup packed)
2 ounces Gruyère cheese, shredded (about 1/2 cup)
1 (12-ounce) package bucatini pasta

Gruyère breadcrumbs

2 tablespoons unsalted butter
3/4 cup panko (Japanese-style breadcrumbs)
2 teaspoons fresh thyme leaves, plus more for garnish
1 small garlic clove, grated with a Microplane grater (about 1/2 teaspoon)
1/2 teaspoon kosher salt
1/2 teaspoon black pepper
1 ounce Gruyère cheese, finely grated with a Microplane grater (about 2/3 cup), plus more for garnish

Directions

Prepare the Pasta

Heat butter and oil in a large Dutch oven over medium. Add onions and 1/2 teaspoon of the salt; stir onions until evenly coated in butter. Cover and cook, stirring occasionally, until onions begin to soften, about 10 minutes. Uncover, and continue cooking over medium, stirring occasionally and scraping browned bits from bottom of pan, until onions are deep golden brown, meltingly soft, and jammy, 50 minutes to 1 hour. Remove 1/2 cup of the caramelized onions, and place in a small bowl; set aside.
While onions cook, prepare the Gruyère Breadcrumbs

Melt butter in a large skillet over medium. Stir in panko, thyme, garlic, salt, and pepper. Cook, stirring constantly, until panko is toasted and golden brown, 4 to 5 minutes. Transfer panko mixture to a medium bowl; set aside to cool until ready to use.
When onions are nearly done caramelizing, bring a large pot of salted water to a boil; add pasta, and cook to al dente according to package directions. Drain pasta, reserving 1/2 cup cooking water.
Once onions are caramelized, stir in sherry, scraping bottom of Dutch oven to loosen and dissolve browned bits. Cook, stirring constantly, until sherry has evaporated and alcohol smell has dissipated, about 1 minute. Stir in flour until onions are evenly coated. Add broth, Worcestershire sauce, fish sauce, pepper, thyme, bay leaf, and remaining 1 1/2 teaspoons salt. Bring to a simmer, stirring often. Continue to simmer, stirring occasionally, until liquid is slightly reduced and thickened, about 5 minutes. Remove and discard thyme sprigs and bay leaf.
Remove Dutch oven from heat; gradually stir in Parmigiano-Reggiano and shredded Gruyère, one handful at a time, until cheeses are melted. Add drained pasta and 1/4 cup of the reserved cooking water; toss until well combined. Continue tossing until a glossy sauce forms that evenly coats pasta, gradually adding remaining 1/4 cup cooking water, 1 tablespoon at a time, if needed. Stir in reserved caramelized onions until evenly distributed.
Divide pasta evenly between 4 bowls. Stir grated Gruyère into Breadcrumbs, and sprinkle evenly over pasta. Garnish with additional thyme leaves and grated Gruyère. Serve immediately.