Preheat the broiler. In a small bowl, cover the bread cubes with the milk and let stand until the milk is absorbed, about 5 minutes.
In a large bowl, mix the beef chuck with the sausage. Add the milk-soaked bread and the eggs, grated cheese, ricotta, garlic, shallot, parsley, salt and pepper and mix thoroughly.
On a large rimmed baking sheet, form the mixture into a 10-by-6-inch meat loaf. Drizzle the top with olive oil and rub the oil over the meat loaf. Broil about 6 inches from the heat for about 5 minutes, until richly browned.
Pour the wine and beef broth into a large slow cooker. Using 2 long spatulas, transfer the meat loaf to the cooker. Cover and cook on high heat for 1 hour. Reduce the heat to low and cook for another hour. Add the mushrooms and cream and cook for 1 hour and 30 minutes longer, until an instant-read thermometer inserted in the center of the meat loaf registers 165° to 170°.
With the same 2 spatulas, transfer the meat loaf to a platter. Pour the cooking liquid into a glass measuring cup and skim off the fat. In a blender, combine half of the mushrooms with the cooking liquid and puree. Transfer the gravy to a sauceboat and stir in the remaining mushrooms. Slice the meat loaf and serve with the mushroom gravy.