Begin by bringing a large pot of salted water to a rolling boil. Add 12 ounces of your chosen pasta and cook until al dente, which usually takes around 8 to 10 minutes. Reserve ½ cup of the pasta water before draining.

In a large skillet, melt 2 tablespoons of unsalted butter with 2 tablespoons of olive oil over medium heat. Add 2 large sliced leeks and cook for about 12 to 15 minutes until golden brown and caramelized.

Once the leeks are caramelized, add 8 ounces of sliced mushrooms and sauté for 6 to 8 minutes until softened. Stir in 2 minced garlic cloves, cooking for another minute until fragrant.

Reduce heat to low, pour in ½ cup of heavy cream, and stir in 1½ cups of shredded Gruyere cheese until melted and creamy.

Toss the reserved pasta into the sauce, folding until thoroughly coated. Add reserved pasta water gradually if the sauce is too thick. Season with salt and pepper.

Plate your Creamy Mushroom Gruyere Pasta, garnishing with freshly chopped parsley if desired. Serve immediately.