Step-by-Step Instructions
Caramelize the Onions:
Heat the butter and olive oil in a large skillet or Dutch oven over medium heat. Add the onions and sugar. Cook, stirring occasionally, until the onions are golden brown and caramelized, about 20–25 minutes.
Add Garlic and Herbs:
Stir in the minced garlic and thyme, cooking for another minute until fragrant.
Incorporate Pasta and Broth:
Add the pasta, broth, and water to the pot. Stir well to combine, ensuring the pasta is mostly submerged.
Cook the Pasta:
Bring the mixture to a boil, then reduce to a simmer. Cover and cook, stirring occasionally, until the pasta is tender and the liquid has reduced, about 12–15 minutes.
Add Cream and Cheese:
Stir in the heavy cream and Gruyère cheese until the cheese is melted and the sauce is creamy. Mix in the Parmesan cheese. Season with salt and pepper to taste.
Serve:
Serve immediately, garnished with fresh parsley or additional cheese if desired.