In a large saucepan, sauté prosciutto and half the sage until fragrant, about 5-7 minutes. Add the cream and bring to a boil, stirring often so the cream does not separate, turn the heat down to medium-low. Add the chopped tomatoes, Parmesan cheese rinds and the roasted mushrooms. Lower heat and simmer; reduce sauce for three hours, adding the remaining sage just before removing sauce from heat.