1. Cook pasta according to package directions, omitting fat and salt. Drain pasta, reserving 1/2 cup pasta water, set aside.
2. Cook bacon in a large nonstick skillet over medium heat until crisp. Remove bacon from pan, reserving 1 tablespoon drippings in skillet. Crumble bacon, set aside. Add crushed red pepper and garlic to pan,- cook 30 seconds. Add spinach, cook 1 minute or just until spinach begins to wilt.
3. Combine pasta, reserved pasta water, bacon, spinach mixture, cheese, and salt, toss gently.