Sauce: Combine tomato sauce, dry sherry, diced tomatoes, sliced mushrooms, cinnamon, clove, brown sugar, oregano, and basil in a sauce pot and bring to a simmer over medium heat. Reduce to medium low and allow to continue simmering for 30 minutes.
Meatballs: combine meats, bread crumbs, crumbled mushrooms, spinach, Parmesan cheese, Worcestershire sauce, and egg in a mixing bowl.
Mix with hands until well blended. (More bread crumbs may be added if mixture is too thin).
Form 2-inch balls and place in an ungreased baking dish.
Bake at 375 for 12 minutes.
Turn and continue to bake for an additional 12 minutes.
Pour sauce over meatballs and sprinkle shredded mozzarella over the top.
Broil on high for 7-10 minutes (until cheese starts to brown).