COOK pasta in Dutch oven or large deep skillet as directed on package, omitting salt. Meanwhile, heat oil in large nonstick skillet on medium-high heat. Add cauliflower and onions; cook 15 min. or until onions are caramelized, stirring occasionally. Add garlic and crushed pepper; cook 1 min., stirring frequently. Add spinach; cover. Cook 5 min. Stir in beans; cook, covered, 2 min. or until spinach is wilted and beans are heated through.
DRAIN pasta; cover to keep warm. Cook broth and Neufchatel in Dutch oven 1 min. or until Neufchatel is completely melted and sauce is well blended, stirring frequently. Remove from heat.
ADD pasta; toss to coat. Stir in cauliflower mixture. Serve topped with nuts and Parmesan.