Ingredients
- 12 oz (340 g) penne, rigatoni, or rotini pasta
- 2 tablespoons butter
- 1 tablespoon olive oil
- 3 large yellow onions, thinly sliced
- 3 cloves garlic, minced
- 2 tablespoons all-purpose flour
- 2 cups (480 ml) beef broth (or vegetable broth for a vegetarian version)
- 1 cup (240 ml) heavy cream
- 1 teaspoon Worcestershire sauce
- 1 teaspoon fresh thyme leaves (or ½ teaspoon dried thyme)
- ½ teaspoon salt
- ½ teaspoon black pepper
- 1½ cups (170 g) shredded Gruyère cheese
- 1 cup (110 g) shredded mozzarella cheese
- ¼ cup (25 g) grated Parmesan cheese
Optional Garnish
- Fresh parsley, chopped
- Extra thyme leaves
Instructions
- Preheat the oven to 375°F (190°C). Lightly grease a 9×13-inch (23×33 cm) baking dish.
- Cook the pasta in salted boiling water until al dente. Drain and set aside.
- Heat the butter and olive oil in a large skillet over medium-low heat.
- Add the onions and cook, stirring occasionally, for 25–30 minutes, until deeply golden and caramelized.
- Stir in the garlic and cook for 1 minute.
- Sprinkle the flour over the onions and cook for 1 minute, stirring constantly.
- Gradually whisk in the beef broth, then add the heavy cream, Worcestershire sauce, thyme, salt, and pepper. Simmer for 3–5 minutes, until the sauce thickens slightly.
- Stir in 1 cup Gruyère, ½ cup mozzarella, and the Parmesan until melted and smooth.
- Add the cooked pasta and toss until evenly coated.
- Transfer the mixture to the prepared baking dish.
- Sprinkle the remaining Gruyère and mozzarella evenly over the top.
- Bake for 20–25 minutes, until the cheese is melted and bubbly. Broil for 2–3 minutes for a golden, lightly browned top, if desired.
- Let the pasta bake rest for 5 minutes, garnish with parsley or thyme, and serve.
Tips
- Take your time caramelizing the onions—they’re the key to the rich, sweet flavor.
- Gruyère provides the classic French onion taste, but Swiss cheese works well too.
- Add cooked shredded chicken, roast beef, or sautéed mushrooms for a heartier meal.
- A splash of dry white wine can be added before the broth for extra depth of flavor.
Storage
- Refrigerator: Store in an airtight container for up to 4 days.
- Freezer: Freeze for up to 2 months. Thaw overnight in the refrigerator before reheating.
- Reheating: Bake at 350°F (175°C) for 15–20 minutes, or microwave individual portions until heated through.
Prep Time: 15 minutes
Cook Time: 55 minutes
Total Time: 1 hour 10 minutes
Servings: 6–8