Preheat the oven to 350 degrees F.

For 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, drop 1 to 1 1/4-inch meatballs onto a sheet pan lined with parchment paper. (You should have about 40 meatballs. They don't have to be perfectly round.) Bake for 30 minutes, until cooked through and lightly browned. Set aside.

In the meantime, for the soup, heat the olive oil over medium-low heat in a large heavy-bottomed soup pot. Add the onion, carrots, and celery and saute until softened, 5 to 6 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 for salt and pepper. 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.