Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.
In a mixing bowl, combine the ground chicken, breadcrumbs, Parmesan cheese, parsley, garlic, salt, pepper, and the egg. Mix well until all ingredients are fully incorporated.
Shape the mixture into small meatballs, about 1 inch in diameter, and place them on the prepared baking sheet.
Bake the meatballs in the preheated oven for about 15-20 minutes or until browned and cooked through.
Meanwhile, in a large pot, heat a little oil over medium heat. Add the chopped onion, carrots, and celery. Sauté for about 5-7 minutes until the vegetables are tender.
Pour in the chicken broth and bring to a boil. Add the dried thyme, paprika, salt, and pepper.
Once the soup is boiling, carefully add the baked meatballs to the pot. Reduce the heat and let it simmer for another 10 minutes.
Stir in the spinach or kale and cook for an additional 2-3 minutes until wilted.
Adjust seasoning if necessary before serving.