Lemon Curd

Zest the lemons; chop the zest. Juice the lemons.

Place butter into a the top of a double boiler, over (not in) gently boiling water. As it melts, add sugar, lemon juice, and lemon zest. Stir frequently until butter is melted and sugar is dissolved.

Strain the beaten eggs into the hot butter/sugar/lemon mixture, stirring constantly with a wire whip. Be patient; almost all the egg will eventually flow through. Straining introduces the egg at a slow rate, preventing curdling, and also leaves hard pieces of albumen behind.

Continue to heat the lemon curd stirring constantly, until it thickens. It will coat a spoon and no longer taste "eggy". Pour into clean glass jars while hot, and refrigerate promptly.