1. Place first 9 ingredients and, if desired, dried crushed red pepper in a Dutch oven in order of ingredient list. Cover and bring to a boil over medium-high heat (about 12 to 15 minutes). Reduce heat to medium-low, and cook, covered, 10 to 12 minutes or until pasta is slightly al dente, stirring at 5-minute intervals.
2. Remove from heat, and stir in shrimp and spinach. Cover and let stand 10 minutes. Stir just before serving. Serve with Parmesan cheese.
Note: We tested with Garofalo Casarecce pasta.