1. In a large pot of salted boiling water, cook the pasta according to package instructions until al dente. Drain the pasta, reserving 1 cup of the cooking water for later use.

2. Heat the olive oil in a large skillet over medium heat. Add the sliced leeks and cook, stirring occasionally, until they’re golden and caramelized, about 20 minutes. If the pan gets too dry, add a splash of water to prevent the leeks from burning.

3. Add the sliced mushrooms to the skillet and continue cooking until they’re tender and browned, about 5-7 minutes.

4. Stir in the minced garlic and cook for 1 minute, until fragrant.

5. Pour in the white cooking broth, scraping up any browned bits from the bottom of the skillet. Let the mixture simmer for 2 minutes.

6. Reduce the heat and stir in the heavy cream. Allow the sauce to simmer and thicken slightly, about 3-4 minutes.

7. Add the cooked pasta to the skillet, tossing to coat it in the creamy sauce. Gradually stir in the shredded Gruyère cheese until it’s melted and the sauce is smooth. If the sauce is too thick, add a bit of the reserved pasta water to reach the desired consistency.

8. Season the dish with freshly ground black pepper and salt to taste. Garnish with chopped fresh parsley, if desired. Serve immediately.