COOK pasta as directed on package, omitting salt. Meanwhile, mix cream cheese spread, milk and Italian seasoning until blended.
HEAT oil in large nonstick skillet on medium-high heat. Add onions and garlic; cook and stir 3 to 5 min. or until crisp-tender.
DRAIN pasta, reserving 1/3 cup cooking water; cover pasta to keep warm. Add reserved water and cream cheese mixture to skillet; cook and stir on medium heat 2 min. Add spinach; cook and stir 2 to 3 min. or just until spinach starts to wilt. Add pasta; stir to evenly coat. Sprinkle with Parmesan.