Active time: 45 minutes Total time: 45 minutes, plus chilling time Serves 4; makes about 16 meatballs

Meatballs:

• One pound ground turkey or chicken (preferably dark meat)
• 1 large egg
• 1/3 cup Panko breadcrumbs (or matzo meal)
• 1/4 cup packed finely grated Parmigiano-Reggiano cheese
• 2 tablespoons finely chopped flat-leaf parsley leaves
• 1 large garlic clove, grated
• 1 teaspoon kosher salt
• 1/2 teaspoon dried oregano
• 1/2 teaspoon freshly ground black pepper

Soup:

• Olive oil
• 1 medium onion, chopped
• 1 large carrot, sliced
• 1 to 2 celery stalks, diced
• Kosher salt
• 5 to 6 cups chicken stock
• 1 (2-inch) chunk Parmigiano-Reggiano rind
• 1 bay leaf
• 1 teaspoon dried thyme
• 1/2 teaspoon freshly ground black pepper
• 2 cups (packed) baby spinach leaves or torn kale leaves
• Grated Parmigiano-Reggiano cheese for sprinkling

Combine the meatball ingredients in a bowl. Gently stir to blend without overmixing.

Using wet hands, form into 1-inch meatballs. Place on a parchment-lined baking sheet.  Refrigerate for at least 30 minutes.

Heat 1 tablespoon oil in a deep skillet or soup pot over medium heat. Add the meatballs in batches, without overcrowding, and flatten slightly. Brown on both sides, turning when they release easily from the pan, about 6 minutes. Transfer to a plate lined with a paper towel. (They will finish cooking in the soup.)

Add 1 tablespoon oil to the pan. Add the onion, carrots, celery, and a pinch of salt. Sauté the vegetables until they are bright and crisp-tender, 3 to 4 minutes, stirring up any brown bits.

Add the stock, cheese hunk, bay leaf, thyme, 1/2 teaspoon salt, and black pepper. Partially cover the pot and simmer over medium heat for about 15 minutes.

Add the meatballs and continue to cook until the meatballs are fully cooked, 8 to 10 minutes more.

Add the spinach and stir until wilted, for 1 to 2 minutes. Taste for seasoning and add more salt if desired.

Ladle into bowls and serve with extra grated cheese for sprinkling.