Heat olive oil in a Dutch oven over medium heat. Add leeks, garlic, and ginger, and sauté until caramelized (about 5-7 minutes).
Add carrots, celery, and butternut squash. Stir for another 3-4 minutes.
Pour in chicken broth and bring to a simmer. Once the vegetables are tender, gently add the meatballs to the pot.
Simmer the soup for another 15 minutes until meatballs are fully cooked through.
Finish with fresh watercress, sage, and parsley for a nourishing touch.