Bring a large saucepan of water to the boil and add the bay leaf salt
Add cauliflower
Cook until still slightly firm, about 10 minutes
Drain the water and set aside
Put the cream in a saucepan and bring to the boil
Boil for 10 minutes, then stir in the mustard and the 1 teaspoon salt
Divide the cauliflower into small florets, then stir into the cream sauce with the egg
Transfer to the prepared baking dish and sprinkle the cheese over the top in an even layer
Bake in a preheated oven at 200°C Gas 6 until golden, about 40~45 minutes
Serve hot