Place a small pot over medium heat with the syrup, heavy cream and cinnamon stick. Bring the liquid up to a bubble then reduce the heat to low and simmer until thickened and reduced, about 15 minutes.
Place the sweet potatoes, carrots, onion, celery and bay leaf into a medium-size stockpot and cover them with cold water. Season with salt and place over medium-high heat, bringing the liquid to a bubble. Reduce the heat to medium and cook the potatoes until tender, 15-18 minutes.
Drain the cooked potatoes and discard the onion, celery and bay leaf. Transfer the potatoes and carrots to a food processor, add a splash of chicken stock and puree until smooth, adding more stock as needed to keep things moving.