How to Make It
Heat oil in a large saucepan over medium-high. Add mushrooms, and cook, stirring often, until all liquid has evaporated, about 12 minutes. Add butter, stirring until melted. Add leeks, garlic, and 1 teaspoon of the salt, and cook, stirring often, until leeks are tender, 4 to 5 minutes.
Stir in pasta, 3 cups water, stock, wine, and remaining 1 1/2 teaspoons salt. Increase heat to high, and bring to a boil. Reduce heat to medium, and simmer, stirring occasionally, until about 3 minutes short of al dente, (check cook time on package). Stir in cream, and simmer until sauce evenly coats pasta, about 3 minutes. Remove from heat. Stir in cheese, herbs, lemon zest and juice, and pepper. Divide pasta evenly among shallow bowls, and serve topped with cheese.