If you love the deep, cozy flavour of French onion soup, this pasta is about to be your new comfort obsession. This French Onion Spaghetti brings together sweet caramelized onions, thyme, and a splash of decadent cognac, all finished with cream and Parmesan for the silkiest, most luxurious bowl of pasta.

It feels a touch fancy, a bit nostalgic, and still simple enough to pull off at home. The onions do most of the heavy lifting, cooking down until jammy and golden before getting folded into a glossy, flavour-packed sauce that clings to every strand of spaghetti. Light a candle, pour a glass of wine, and pretend you’re in a tiny bistro.

Why You’ll Love this Recipe:

• Deep, caramelized flavour: Slow-cooked onions create a rich, savoury base that gives the whole dish serious depth.
• Silky, glossy sauce: Cream and Parmesan create a smooth sauce that coats every strand of pasta.
• Simple ingredients, elevated result: Mostly pantry staples and onions, but the flavour feels layered and complex.
• Comforting but refined: It hits that cozy pasta craving while still feeling a little special.
• Great for slower evenings: Perfect when you want to cook something a bit more intentional without it being complicated.

Prep for French Onion Spaghetti:

• Chop the onions in half, then cut into thin slices.
• Rinse the fresh thyme and any other herbs you’re using for garnish.
• Finely grate the parmesan cheese (I like using a microplane grater for the fluffiest texture).

How to Make French Onion Spaghetti:

Step One:

In a large skillet over medium heat, melt the olive oil and butter together. Add the sliced onions and cook, stirring occasionally, until softened, about 5 minutes. Season with a generous pinch of salt and a few cracks of black pepper.

Step Two:

Continue cooking, stirring every few minutes, until the onions are deeply golden and caramelized, 30–35 minutes. During the last 5 minutes, add the thyme sprigs.

Step Three:

Meanwhile, bring a large pot of water to a boil. Salt it generously, then cook the spaghetti until al dente. Reserve ½ cup of the pasta water, then drain.

Step Four:

Lower the heat under the onions and remove the pan from the burner. Carefully add the cognac, then return the pan to low heat. Simmer for 2-3 minutes, scraping up any browned bits, until the alcohol cooks off.

Step Five:

Stir in the sherry vinegar, Worcestershire sauce, and beef stock. Increase heat to medium-low and let simmer until slightly reduced and thickened, about 5 minutes. Stir in the heavy cream and cook for 2 minutes more. Remove and discard the thyme sprigs.

Step Six:

Add the spaghetti directly to the sauce and toss to coat, adding a splash of reserved pasta water as needed to loosen the sauce to your preferred consistency.

Step Seven:

Serve into bowls and top with freshly grated Parmesan and fresh herbs.

Substitutions for French Onion Spaghetti:

Yellow onions: Sweet onions or white onions will both work well, but yellow are the most classic for a French onion recipe.

Cognac: Dry white wine, brandy, or even a splash of dry sherry. If avoiding alcohol, omit and use a bit of extra stock to deglaze.

Sherry vinegar: Red wine vinegar or balsamic vinegar (use a little less balsamic since it’s sweeter).

Worcestershire sauce: A small splash of soy sauce or tamari for that savoury depth.

Beef stock: Vegetable or chicken stock will work here too for a lighter flavour.

Heavy cream: Sub half-and-half or light cream for a lighter option.

Parmesan: Gruyère, Comté, or Pecorino Romano all pair beautifully with the French onion flavours.

Spaghetti: Any long pasta like linguine, fettuccine, or bucatini. Short pasta like rigatoni or penne also works if you prefer.

How to store French Onion Spaghetti:

Store any leftovers in an airtight container in the fridge for up to 3 days. The sauce will thicken as it cools, so when reheating, add a splash of water, broth, or cream to loosen it up and bring back that silky texture.

I’m obsessed with how cozy and luxurious this one is! If you try it out, tag me on social—@britacooks! xx