Cook pasta according to package instructions, or until al dente. Rinse with warm water, drain and set aside.
Meanwhile, sauté leeks or onions in olive oil for 1 minute, until limp. Add mushrooms and garlic and continue sautéing for 3 minutes until mushrooms are tender. Add cream and bring to simmer. Reduce heat and add cheeses, stirring constantly, just until melted. Add chives and pasta; stir well.
Spoon into serving dish and, if desired, sprinkle with additional pepato cheese. Serve immediately.