2) Wipe mushrooms clean with damp towel. Remove woody stems. Thinly slice the mushrooms.
3) Heat a large deep skillet with extra-virgin olive oil over medium-high heat. Add the mushrooms and cook until deeply golden and tender, 10 mins.
4) While mushrooms cook, halve the leeks lengthwise. Cut off about 5cm from tough tops. Trim off root end. Thinly slice the leek then vigorously wash in a large bowl of cold water, separating all the layers to free of grit. Let leeks sit a few minutes then lift out of the water and dry on kitchen towel.
5) Add leeks to mushrooms along with garlic and season with salt, pepper and fresh thyme. Cook 3 to 4 mins more then add wine, reduce half a minute then stir in cream and heat through. Toss pasta with mushrooms and adjust seasoning. Top with grated cheese at the table.