Special Fish Pie

1. Dip fish in a little flour and lay half in an ovenproof dish.
2. Melt butter, stir in flour, gradually stir in milk and cook gently until thickened.
3. Add mustard powder, 4 oz cheese and seasoning.
4. Stir until cheese is melted and then add onions and prawns.
5. Pour half the sauce over the fish in dish.
6. Place remainder of fish on top and cover with rest of sauce.
7. Sprinkle remaining cheese on top.
8. Cook in a pre-heated oven 160°C/325°F/Gas 3 for 40 minutes.
9. Serve on a bed of rice.