1/2 cup butter
1-1/2 cups sugar
1/2 cup lime juice
Grated zest of two limes
6 eggs, lightly beaten
Put all ingredients, except eggs, into double boiler over simmering water. When butter has melted and before mixture is too warm, gradually whisk in the beaten eggs. Cook, stirring constantly, until thickened to consistency of instant pudding, at least 10-15 minutes. Remove from heat and cool for a while. Then place in a container, cover, and store in the refrigerator.