In large saucepan, cook fettuccine to desired doneness as directed on package. Drain; cover to keep warm.
Meanwhile, heat oil in large skillet over medium-high heat until hot. Add chicken, leeks and garlic; cook and stir 4 to 5 minutes or until chicken is no longer pink. Add tomatoes, ham, oregano and broth. Bring to a boil. Reduce heat; cover and simmer 5 minutes.
In small bowl, combine cornstarch and half-and-half; blend until smooth. Gradually stir into mixture in skillet. Cook and stir over medium-high heat until mixture boils and thickens, stirring constantly. Serve over fettuccine.