Season chicken w/ salt and pepper. In a large frying pan, heat butter and oil over medium heat. Add chicken and cook until brown, about 5-6 min. Remove and set aside.
Add onions to the pan. Cook until onion is soft, about 3 min. Add garlic cook another 30 seconds. Stir in tomatoes, tomato paste, and stock. Add cinnamon stick. Bring to a boil and return chicken to pan. Cover, reduce heat, and simmer 30 minutes, until tender.
Serve over cooked orzo.