Ingredients
Equipment
Method
- Preheat your oven to 375°F (190°C).
- Melt the butter in a large oven-safe skillet or Dutch oven over medium heat. Add the onions, salt, and pepper. Cook for 20 to 25 minutes, stirring often, until the onions are deeply caramelized.
- Stir in the thyme and garlic. Cook for 1 minute, then sprinkle the flour over the onions. Stir and cook for another 1 to 2 minutes.
- Pour in the wine, scraping up any browned bits, and cook until mostly evaporated, about 2 minutes. Stir in the beef broth and bring to a simmer.
- Meanwhile, cook the pasta in a large pot of salted boiling water until just shy of al dente. Drain well.
- Add the pasta to the onion mixture and stir to coat. Sprinkle with Gruyère, mozzarella, and Parmesan cheese.
- Transfer the skillet to the oven and bake for 15 to 20 minutes, until the cheese is melted and bubbly.
- Serve hot, garnished with extra thyme if desired.
Nutrition
Notes
Be patient with onions. Don’t rush them. The flavor comes from letting the onions cook down until they’re jammy and golden. Dry white wine adds great depth, but extra beef broth works perfectly if you prefer not to use it. Salt the pasta water. The pasta should be well seasoned before hitting the skillet, since the sauce stays mild and brothy. Gruyère gives the dish its signature French onion flavor, mozzarella melts for stretch, and Parmesan adds sharpness. Watch the bake time. You want the top deeply golden but not too dark. Pull it once the edges bubble and the cheese browns beautifully. You can assemble this dish without baking, cover, and refrigerate up to one day. Bake uncovered, adding 5 to 10 minutes as needed. This dish reheats nicely in the oven.