I got the method and proportions from following what Alton Brown did on his Good Eats episode intitled, “The Egg Files”. According to him, this stuff keeps up to a month in the refrigerator.
Yield: a medium-sized bowl
|—||1" of water in a double boiler|
|¼ lb||high-grade, unsalted butter, cold|
1. Cut butter into roughly 1 tbsp pieces.
2. Rasp off just the yellow, outer skin of the lemon zest. Cut and juice two of them (or one more) to yield one-third of a cup of juice. Dump in the sugar. Wisk in the 5 egg yolks mixing all ingredients well.
3. Over the double boiler, wisk the entire mixture constantly to keep the egg from cooking for between 7 to 10 minutes. The end result should be creamy and nap the back of a wooden spoon as would custard or pudding.
4. Remove from heat and begin wisking in 1-2 pieces of butter at a time until all incorporated. Set aside to cook. Beat later if desired.
4. Serve over cake or use as a garnish.