Cook the pasta according to package directions, drain and cool. While the pasta is cooling, in a large bowl, mix the mayonnaise, Parmesan cheese, shredded chicken breast, salt, pepper and milk until smooth. If it seems little too thick, add a touch more milk.

Add the cooled pasta to the mayonnaise mixture and mix well. Add the green onions and tomatoes and mix again. Chill for several hours.

Serve on a bed of lettuce.