Combine the
first five ingredients in a pot. Stir till boiling, reduce heat to
simmering point. Beat egg yolks in a small bowl. Pour a ladle of the hot
agar-agar mixture into the egg yolk, stirring till well mixed. Then pour
egg back into pot. Stir to mix well. Put in the butter and stir till it
melts. Remove from heat and pour into a rinsed mould. Leave to set
before turning out.