Season the diced chicken with salt, black pepper, garlic powder, onion powder, and Herbes de Provence in a medium bowl.
Warm the olive oil in a large Dutch oven over medium-high heat.
Add the chicken pieces and sauté them until they develop a golden-brown color and are cooked through, about 6 to 8 minutes.
Transfer the cooked chicken to a plate and set aside.
Lower the heat to medium and melt the butter in the same pot.
Add the chopped onion, celery, and shredded carrots and cook for around 4 minutes until the vegetables soften and produce a fragrant aroma.
Sprinkle the flour over the vegetables and mix well to coat them, cooking briefly until the flour is no longer visible.
Gradually whisk in the chicken broth and heavy cream, blending everything together smoothly.
Mix in the Italian seasoning, dried thyme, and ground nutmeg.
Bring the mixture up to a gentle boil, then reduce the heat to maintain a simmer.
Return the cooked chicken to the pot and stir in the fresh spinach and gnocchi.
Cover the pot and simmer for about 8 minutes until the gnocchi becomes tender and the soup reaches the desired thickness.
Season with additional salt and pepper to taste.
Serve the soup warm and enjoy it with garlic breadsticks if desired.