- Heat oil in Dutch oven or soup kettle over medium-high heat.
- Sauté carrot, onion and celery for 5 minutes; stir in broth, chicken, peppercorns, thyme and bay leaves.
- Reduce heat to low; simmer, partially covered for 20 minutes.
- Meanwhile, in small bowl, mix dumpling ingredients until well blended.
- Drop small spoonfuls of dumpling dough into simmering soup.
- Cover soup and allow dumplings to cook for about 20 minutes (they will rise to the top of the soup as they cook).
- Stir in spinach.
- Remove bay leaves before serving soup.