COOK pasta as directed on package, omitting salt.
MEANWHILE, cook and stir chicken and garlic in hot oil in large deep skillet or Dutch oven on medium-high heat 3 min. or until chicken is no longer pink. Add sauce and crushed pepper; simmer on medium-low heat 8 to 10 min. or until chicken is done, stirring occasionally. Add spinach; cook 1 min. or just until wilted, stirring frequently.
DRAIN pasta. Serve topped with chicken mixture and cheese.