Sauté onion, carrots, and celery with 1/4 tsp salt and 1/2 teaspoon pepper until softened and just starting to brown. Add garlic and cook for 1 minute, until fragrant.
Gradually whisk in chicken stock and simmer to thicken slightly. Whisk in half and half, thyme, and Italian seasoning. Bring to a simmer (not a rolling boil), stirring or whisking.