Discard any bruised leaves and surplus stem from fennel bulbs, and cut each in half, lengthwise.
Wash thoroughly in cold water.
Put fennel halves in a large saucepan, and fill with cold salted water.
Bring to the boil, and cook until tender.
Drain well, and place in a well-buttered shallow earthenware dish.
Season with salt and pepper, and dot with butter.
Sprinkle liberally with Parmesan cheese, and bake in a fairly hot oven, 200°C/Gas Mark 6/400°F, until top is golden brown.