
In a Dutch oven, melt the butter over medium heat. Add the celery, carrots, onion and garlic. Cook and stir until they're crisp-tender, four to six minutes. Editor's Tip: The vegetables should soften but still have some bite to them.
Stir in the flour until it's blended in. Gradually whisk in the broth, and bring the soup to a boil. Reduce the heat and simmer the soup, uncovered, until it is slightly thickened, four to five minutes, stirring occasionally.
Stir in the gnocchi and chicken. Cook until the gnocchi is heated through and tender, four to six minutes. Editor's Tip: You can cut a gnocchi down the middle to test for doneness. If it's tender and warm in the middle, it's finished cooking!
Reduce the heat to medium-low. Stir in the spinach, cream, thyme, salt and pepper, and heat them through. Garnish the soup with chives.