Slice tough bottom end from 1 large fennel bulb and discard. Thickly slice lengthwise. Arrange in a single layer in a large frying pan. Add 1 cup chicken broth, 1/4 cup freshly squeezed orange juice and 1 tbsp butter. Cover and bring to a boil. Then reduce heat to medium-low and simmer, covered, until fennel is tender, about 18 to 20 min. Remove fennel to a shallow serving dish. Bring broth to a boil. Continue boiling until sauce is slightly reduced, about 2 to 3 min. Stir in zest from orange. Pour sauce over fennel.