Rinse the mushrooms well under cold water. Add 1/2 cup of hot water to 1/2 c wine and soak mushrooms to re-hydrate while starting the sauce. Mix spices in a small bowl and set aside. Dissolve tomato paste in beef broth.
In a large skillet, heat 2 tbsp oil over medium heat. Add the diced pancetta and cook, stirring, until well browned and the fat is rendered. Remove pancetta from skillet and place in a large pot for the sauce.
Add the beef, lamb, and sausage to the skillet in small batches to brown the meat (adding too much meat at once will steam the meat instead of browning it). Add a small amount of wine at the end of each batch to loosen browned bits from the skillet. Once browned, add meats to the large pot.
Add the onions, carrots, and celery to the skillet with 1 tbsp oil and cook, stirring, until soft, 4 to 5 minutes. Add the garlic, pepper, bay leaves, basil, thyme, oregano, cinnamon, and nutmeg and cook, stirring, until spices are fragrant.
Add the other 1 cup of wine and cook, stirring, to deglaze the pan and remove any browned bits sticking to the bottom of the pan, and until half of the liquid is evaporated, about 2 minutes. Remove from skillet and add to the large pot with the meats.
Add the tomatoes and their juices, the tomato sauce, tomato paste and beef broth mixture, and sugar; bring to a low boil. Drain the mushrooms, reserving the liquid. Add mushrooms to the sauce and strain the reserved liquid through a piece of doubled cheesecloth to remove any sediment;
add reserved liquid to the pot. Reduce the heat to medium-low or simmer, stirring occasionally, to keep the sauce from sticking to the bottom of the pan, until the sauce is thickened and flavorful, at least 2 hours (longer is better!).
Toward the end of the simmering time, add the cream, butter, and parsley, stir well, and simmer for 5 minutes. Discard the bay leaves and adjust the seasoning, to taste. Remove from the heat and cover to keep warm until ready to serve.
Place a serving of spaghetti on a plate and cover with sauce, add a couple serving spoons of ricotta on top. Add grated Parmesan on top of that and serve. Alternatively, serve this "family style" on one large platter as described for individual servings.