Continue until
all the
butter is used up. It should take about 2 minutes, at which point the
sauce will be thick. If at any point you sense that the is about to separate, quickly add a teaspoon of cold
milk or
cream. Now whisk in about 1 more teaspoon of
lemon juice, a pinch of
salt, and optional
cayenne.
Taste to see that the
sauce is lemony enough for your
taste.