Place cod filets in the bottom of a round oven dish.  Make a cheese sauce with butter, flour, milk and grated cheese:  pour over fish. 

 

Scone dough:  mix butter into flour with baking powder, and salt.  Add 2 oz grated cheese, preferably mature Cheddar or a mixture of that and Parmesan.  Drop egg yolk into the mixture and add enough milk to make a workable dough.  Roll out to a thickness of 1/2" and cut into small rounds with a scone cutter.

 

Dispose the scone rounds over the fish and sauce, so that they just about cover the surface; glaze them with a little milk, sprinkle some more grated cheese over them and bake in a hot oven ( 450 degrees F ) for 25-30 minutes, until the scones are golden brown.