Melt the butter in a heavy saucepan, stir in the cheese and add salt, pepper and mustard if liked. Stir over a gentle heat until the cheese melts.

This mixture may be used as it is, or can be bound with egg yolks if the butter and cheese show signs of separating. The beer should be stirred in last, if using.

Spread the toast slices with the mixture and brown under a preheated grill for 3-4 minutes.

Buck Rarebit

Buck rarebit is Welsh rarebit with a poached egg served on top of each slice.