Combine bread pieces and whole milk in medium bowl, pressing on bread to submerge.
Squeeze out most of milk from bread; discard milk.
Place bread in large bowl. Add ground meat, eggs, finely chopped onion, parsley, sage, garlic, and salt, pepper.
Working in 2 batches if necessary, transfer meat mixture to the food processor, process until well blended and mixture looks pasty.
Form mixture into 1 3/4-inch-diameter meatballs (about 30). Divide meatballs between two 13x9x2-inch glass baking dishes. Bake meatballs 30 minutes. Set meatballs aside.
Dust meatballs with flour; shake off excess.
Melt butter with oil in a heavy large skillet over medium-high heat. Working in batches, add meatballs to skillet and sauté until brown on all sides, about 3 minutes.
Return all meatballs to skillet.
Whisk wine and tomato paste in small bowl to blend. Add wine mixture to meatballs and bring to boil.
Continue boiling until wine thickens slightly, stirring frequently, about 5 minutes.
Add broth, reduce heat to medium and simmer until flavors blend and gravy thickens, stirring frequently, about 15 minutes.
Season to taste with salt and pepper. Transfer meatballs and gravy to bowl. Sprinkle with remaining parsley and serve.
Notes
Tips for Making Great Meatballs
Don't overmix the meat! You wamt tender, losely compacted meatballs, not a tightly-packed sausage. You'll get more a more evenly cooked and better tasting meatball this way.
Regardless of the meat you use, make sure it has a minimum fat to lean ratio of 20:80. If the meat is too lean you will end up with a less flavorful and dryer meatball.
Added ingredients mean added flavor! Think of toasted nuts, fresh herbs and other seasoning. Fresh is always best!