In a large pot, cook carrot, celery, and onion in the melted butter over medium heat until the vegetables are tender.
Season with salt and pepper. Add the wild rice, chicken stock, rosemary, thyme, celery seed, and bay leaves.
Raise the heat slightly to allow soup to simmer, covered, for 20 minutes.
Add chicken pieces, simmer for approximately 20 minutes more until chicken is cooked and rice is tender.
To finish the soup, add zest of one lemon and lemon juice, whole milk, and cream. Season with more salt and pepper to taste.
To thicken the soup, melt 1⁄4 cup of butter in a separate small pot and whisk 1⁄4 cup of flour into it and stir for a minute or two.
Add this flour and butter paste to the soup to thicken. Repeat if you like your soup extra thick.
Bring the soup back up to temperature and serve with fresh thyme sprinkled on top.
Notes
I highly recommend using homemade bone broth for superior flavor and nutrition.
The longer the soup sits, the more the flavors develop, so if you’re able to make it earlier in the day and have it sit for several hours in the fridge before reheating it, the lemon flavors really come out best.