1. Arrange the fish fillets in a greased shallow baking pan.
2. Brush with a little butter and sprinkle with mustard and salt.
3. To the remaining melted butter add the flour.
4. Gradually add the milk stirring all the while to avoid lumps.
5. Bring to a boil and add the cheese.
6. Add the salt and simmer till the cheese has melted.
7. Remove from the fire, add the parsley and pour the sauce over the fish fillets.
8. Bake in a moderate oven (177oC) for 30 minutes.

Note:
Fish and cheese are high in protein. To find out the importance of including proteins in our diet, click here