In a large heavy pot, heat olive oil over medium high heat. Add onion, garlic and prosciutto and sauté until softened. Add clams, white wine, saffron, chicken stock and tomato sauce and bring to a boil.
Add cooked gemelli pasta to pot and heat through completely. Make sure that all of the clams have opened. Discard any un-opened clams. Add chili flakes and parsley. Season to taste with salt, if necessary.
Serve immediately