Bring a large pot of lightly salted water to a boil. Add pasta and cook for 8 to 10 minutes or until al dente; drain.
Melt butter in a large frypan over low heat. Saute leeks and garlic until tender and translucent. Stir in cream and simmer until thickened. Toss with pasta and cheese until evenly coated and cheese is melted. Season with pepper.