Lemon Curd

Place the egg yolks into the top of a double boiler or a heat-proof bowl. Beat vigorously for a minute. Add sugar and beat for another minute. Add lemon juice and zest and give it another good stir. Place bowl over a pot of simmering water (make sure the bowl isn't touching the water). Cook, stirring, until the mixture thickens. This can take anywhere from 10 to 20 minutes. Stir in the butter a piece at a time, whisking until each piece is nearly completely melted before adding another one. Strain mixture through a fine-mesh sieve into a storage container. Cool for a bit. Cover and refrigerate for at least 2 hours before serving. Will keep for about 5 –7 days in the refrigerator. Recipe adapted from Williams-Sonoma.