Lemon Meringue Custards

In a food processor grind the sugar and the zest until the zest is chopped fine and transfer the mixture to a large saucepan. Add 1/4 cup water, bring the mixture to a boil over moderate heat, stirring until the sugar is dissolved, and boil the syrup for 5 minutes. Stir in the milk, the cream, and the salt and cook the mixture until it is hot, but do not let it boil. In a bowl whisk together the yolks and the whole eggs, add the hot milk mixture in a stream, whisking, and stir in the lemon juice. Strain the custard through a fine sieve into twelve 2/3-cup ramekins set in a large baking pan, add enough hot water the pan to reach halfway up the sides of the ramekins, and bake the custards in the middle of a preheated 325 °F. oven for 40 minutes, or until they are just set. (Alternatively, the custard can be baked in the same manner in a 1 1/2-quart shallow baking dish for 1 hour, or until it is just set.) Remove the ramekins from the pan, let the custards cool completely, and chill them, covered loosely with wax paper, for at least 3 hours. The custards may be made 1 day in advance and kept covered and chilled.