Cook pasta according to package directions; drain pasta, reserving 3/4 cup of the cooking water. In a very large skillet heat oil over medium heat; add cauliflower and salt, stirring to coat. Cook about 8 minutes or until tender and lightly browned, stirring occasionally.
Uncover skillet and add chicken and raisins. Cook and stir for 2 to 3 minutes more or until heated through. Add pasta and the reserved cooking water to skillet; cook and stir until heated through. Remove from heat. Stir in arugula; top with hazelnuts and shaved Parmesan.