Bake for about 10 minutes until just starting to brown on the top.
Serve immediately.
Remarks
As well as whiting, you can use other sea fish, such as sole, or freshwater fish, such as pike or zander.
If you do not have any fish stock for poaching the mousselines, use a vegetable stock instead, or - at a push, as it is not quite as good - just salted water.
Serve 2 mousselines per person as a starter, 4 as a main course.