Place the chicken breasts in a 6-quart slow cooker.
Top the chicken with diced onion, minced garlic, diced celery, and shredded carrots.
Sprinkle in the dried basil, Italian seasoning, ground nutmeg, bay leaf, and a generous pinch of salt and pepper.
Pour the chicken broth over the chicken and vegetables. Cover.
Slow Cooking
Cook on high for 3-4 hours or on low for 6-8 hours, until the chicken is fully cooked and tender.
Remove the chicken to a cutting board. Discard the bay leaf. Shred or chop the chicken into bite-sized pieces and return it to the slow cooker.
Final Cooking
Stir in the heavy cream. Add the gnocchi. Cook on high for 30-45 minutes, until the gnocchi are tender and the soup has thickened slightly. Check after 25-30 minutes.
Toss in the fresh spinach. Cover and let sit for 5 minutes so the residual heat wilts the spinach.
Taste and adjust seasoning with salt and pepper. Serve hot.
Notes
For a thicker soup, mash a few gnocchi against the side of the pot or stir in a teaspoon of cornstarch slurry at the end. Serve with grated Parmesan, garlic toast, or a simple arugula salad.