In a saucepan, heat the chicken broth until barely simmering; cover to keep hot. In another saucepan, heat the olive oil over medium heat. Add the onion, garlic and prosciutto and cook, stirring occasionally, until the vegetables are soft, 5 minutes. Add the rice and lightly toast 2 minutes.
Lower the heat to medium-low, add the wine and saffron and cook for 2 minutes. Add 1 1/2 cups of the heated chicken broth and cook, stirring, until the liquid is almost absorbed, 5 minutes. Add another 1 1/2 cups broth and cook, stirring constantly, until the liquid is almost absorbed. Repeat with another 1 1/2 cups broth. Working with 1/4 cup at a time and stirring to let it absorb, continue adding the remaining broth until the risotto is tender and creamy.
Stir in the scallops and cook until opaque, about 3 minutes. Stir in the parsley, cheese and butter.