In a mixing bowl, combine all meatball ingredients: beef, turkey, breadcrumbs, parsley, Parmesan, egg, salt, and pepper. Gently mix—do not overwork. Shape into very small meatballs, about ¾″–1″ rounds.

Heat 1 Tbsp olive oil in a large pot over medium‑high heat. Brown meatballs on all sides (~5–6 minutes), then transfer to a paper‑towel lined plate. They will finish cooking in the soup.

In the same pot, add another 1 Tbsp olive oil. Sauté carrots, onion, and celery until softened (~6–8 minutes). Season with salt, pepper, and Italian seasoning. Add garlic and cook until fragrant, ~1 minute.

Stir in orzo pasta, then pour in chicken broth and bring to a boil.

Add the browned meatballs. Reduce heat to medium‑low so the broth simmers gently. Cook uncovered for ~10 minutes, stirring occasionally, until pasta is al dente and meatballs are fully cooked.

In the final minute of cooking, stir in baby spinach until wilted.

Ladle soup into bowls and top with generous shreds of Parmesan cheese. Serve hot.