Layer chopped Neuadd Fach Baconry Bacon , sliced potato, and finely sliced onions in a casserole dish, finishing with potatoes. Melt 1oz butter, add 1 tablespoon flour, gradually add ½ pint milk and grated cheese. Pour sauce over the bacon mix. Cover and cook for 1 hour at Gas mark 4. Take off lid and cook for a further hour until brown.