Cut the tops off the bell peppers and remove the seeds. Make a small cut at the base to help the peppers stand upright.
In a bowl, mix the ground chicken with the remaining ingredients and fill the peppers with the mixture. Place the stuffed peppers on a baking sheet and bake at moderate heat for about 75 minutes, or until the chicken is cooked through. Serve with the sweet potato purée.

Place the sweet potatoes and salt in a pot of water. Cook until the sweet potatoes are tender.
Add the cinnamon and butter, then mash until smooth.
Spread the sweet potato purée on each plate and place the stuffed peppers on top.