Bake 28 to 30 min. or until chicken is done (165ºF). Meanwhile, cook pasta in large saucepan as directed on package, omitting salt. While pasta is cooking, grate zest from 1 lemon; set aside. Squeeze juice from both lemons into small saucepan; add broth. Bring to boil; simmer on medium heat 6 to 8 min. or until slightly thickened. Add butter and lemon zest; simmer 3 to 4 min. or until butter is melted and mixture is well blended, stirring occasionally.