• Heat 2 tablespoons of olive oil and 2 tablespoons of butter in a large skillet over medium heat. Add the sliced leeks and season with ½ teaspoon salt and ½ teaspoon sugar. Cook the leeks, stirring occasionally, until they are golden and caramelized, about 20 minutes. If the pan becomes too dry, add 1-2 tablespoons of water. Once cooked, remove the leeks from the pan and set them aside.
• In the same skillet, melt the remaining 1 tablespoon of butter. Add the mushrooms in a single layer, ensuring they have enough space to brown. Let them cook for about 4 minutes before flipping them over and allowing them to brown on the other side. Season with salt and pepper to taste.
• Add the minced garlic and sage to the skillet and sauté for 1 minute, until fragrant. Return the leeks to the pan and stir in the heavy cream, balsamic vinegar, and lemon zest. Bring to a simmer and cook for 2-3 minutes until the sauce thickens. Season with salt and pepper to taste.
• While the sauce is simmering, cook the fettuccine in a large pot of salted water until al dente. Reserve 1 cup of the pasta cooking water before draining the pasta.
• Add the cooked fettuccine and reserved pasta water to the sauce. Stir in the grated gruyere cheese and black pepper and toss the pasta to coat with the sauce. Let it simmer for an additional 2 minutes until the cheese is melted, and the pasta is well coated. Taste and adjust seasoning with salt and pepper as needed.
• Divide the pasta into 4 bowls and top with toasted pine nuts. Serve immediately.

Details:

• This creamy mushroom and leek fettuccine offers a rich and savory sauce balanced by the slight sweetness of caramelized leeks and the earthiness of oyster mushrooms. The pine nuts add a delightful crunch for extra texture.