Ingredients
Scale
For the caramelized onions:
- 4 large yellow onions, thinly sliced
- 3 tablespoons butter
- 2 tablespoons olive oil
- 1 teaspoon salt
- 1 teaspoon sugar
- 3 cloves garlic, minced
- 1/2 cup dry white wine (or additional beef broth)
- 2 teaspoons fresh thyme leaves
For the pasta:
- 1 pound ziti or penne pasta
- Salt for pasta water
For the sauce and assembly:
- 3 cups beef broth
- 1 tablespoon Worcestershire sauce
- 1 teaspoon Dijon mustard
- 1/2 teaspoon black pepper
- 2 cups shredded Gruyère cheese, divided
- 1 1/2 cups shredded mozzarella cheese, divided
- 1/2 cup grated Parmesan cheese
- Fresh thyme for garnish (optional)
Instructions
- Heat the butter and olive oil in a large, deep skillet or Dutch oven over medium heat. Add the sliced onions, salt, and sugar.
- Cook, stirring occasionally, for 35-40 minutes until the onions are deeply golden and caramelized. Lower the heat if they start to burn.
- Add the garlic and thyme, cooking for another minute until fragrant. Pour in the wine and scrape up any browned bits from the bottom of the pan.
- While the onions are caramelizing, bring a large pot of salted water to a boil. Cook the ziti according to package directions until just al dente (it will cook more in the oven).
- Drain the pasta and set aside.
- Preheat your oven to 375°F. Add the beef broth, Worcestershire sauce, Dijon mustard, and black pepper to the pan with the caramelized onions.
- Bring to a simmer and cook for 5 minutes. Taste and adjust seasoning if needed.
- Add the cooked pasta to the pan along with 1 cup of the Gruyère and 1 cup of the mozzarella. Stir everything together until the cheese starts to melt.
- Transfer everything to a 9×13-inch baking dish if you’re not using an oven-safe pan. Top with the remaining Gruyère, mozzarella, and all of the Parmesan.
- Bake for 25-30 minutes until the cheese is melted and golden brown on top. For extra browning, turn on the broiler for the last 2-3 minutes, watching carefully.
- Let it rest for 5 minutes before serving. Garnish with fresh thyme if you’d like.
- Prep Time: 15 minutes
- Cook Time: 1 hour 15 minutes
