To make the meatballs~ place the ground chicken, sausage, bread crumbs, garlic, parsley, Pecorino, Parmesan, milk, egg, 1 teaspoon salt, and 1/2 teaspoon pepper in a bowl and combine gently with a fork. With a teaspoon or small portion scoop, drop 1 to 1 1/4-inch meatballs onto a sheet pan lined with parchment paper. (Makes about 40 meatballs.) Bake for 30 minutes, until cooked through and lightly browned. Set aside.
While the meatballs ar baking, prepare the soup broth: heat the olive oil over medium-low heat in a large pot. Add the onion, carrots, and celery and saute until softened, about 5 minutes, stirring occasionally. Add the chicken stock and wine and bring to a boil. Add the pasta to the simmering broth and cook for 6 to 8 minutes, until the pasta is tender. Add the fresh dill and then the meatballs to the soup and simmer for 1 minute. Taste, and add salt and pepper if needed. Stir in the fresh spinach and cook for 1 minute, until the spinach is just wilted.
Ladle into soup bowls and sprinkle each serving with extra grated Parmesan.