Welsh Rarebit (British toast dish)
Unlike cheese simply melted on toast, Welsh rarebit starts with a smooth cheddar sauce built on flour and milk, spread thick and flashed under the broiler until it bubbles and spots brown. Dijon mustard and Worcestershire sharpen the cheese. To keep the fat from separating, the cheddar is grated ahead and added a handful at a time over the lowest heat, never at a hard boil. Lightly toasting the bread first keeps it from turning soggy under the thick topping. Under the broiler it needs watching the whole time, since the top goes from bubbling to burnt quickly.