A couple things are critical. Use fresh young carrots, and use the orange rind. If you don't have an orange put a little orange juice in...........it adds some depth and sweetness. We have found Chicken Bone Broth is too strong for the delicate flavours so do use a cheaper less intense stock.
Melt butter in saucepan and add chopped carrots, onion and rice. Stir often and sauté for 5 minutes. Do not brown. Add chicken stock and orange rind, bring to a boil, partially cover and reduce heat to simmer for about 45 minutes. Test that carrots are tender.