In a large saucepan, cook pasta for 8 - 10 minutes or until tender.
Heat Dutch oven over medium high heat until hot. Cook prosciutto in single layer until crisp, about 30 second per side. Remove to paper towl and pat off excess fat. Let cool; cut into thin strips.
Add oil to same pan. Add onion, yellow pepper and mushrooms; cook over medium high heat, stirring often, until onions and peppers are soften, about 3 minutes. Add garlic, oregano and pepper flakes; cook for about 15 seconds.
Add tomatoes and bring to a boil; reduce heat and simmer briskly for 3 minutes. Stir in spinach until wilted, about 30 seconds.
Drain pasta and toss with sauce.
Sprinkle wit prosciutto strips and parmesan cheese.