Bring a large pot of salted water to boil. Add your pasta and cook according to package instructions until al dente. Reserve about half a cup of pasta water before draining.

In a large skillet over medium heat, add olive oil. Once hot, toss in the sliced leeks and sauté until they begin to caramelize—about 5 minutes. Next, add in the sliced mushrooms and cook until they're tender and browned.

Stir in minced garlic and cook for another minute until fragrant. Then pour in your broth (or vegetable stock) and bring it to a simmer.

Lower the heat and stir in heavy cream while scraping any bits from the bottom of the pan. Gradually mix in shredded Gruyere cheese, stirring continuously until melted and creamy.

Add your drained pasta into the skillet with the sauce along with some reserved pasta water if needed to reach desired consistency. Sprinkle in black pepper and salt to taste; mix everything together gently but thoroughly.

Garnish with chopped fresh parsley if desired before serving. Enjoy every spoonful!