Ingredients
Preparation
Step 1
In a small heavy saucepan combine 3/4 cup of the sugar, the cream of tartar, and 1/4 cup water, bring the mixture to a boil, stirring until the sugar is dissolved, and boil the syrup, covered, for 1 minute. Remove the lid and boil the syrup, undisturbed, until it begins to turn golden. Continue to boil the syrup, swirling it and tilting the pan occasionally, until it is a deep golden caramel. Pour the caramel into a loaf pan, 9 1/4 by 5 1/4 by 3 inches, tilt the pan to coat the bottom and sides with the caramel, and let the caramel cool.
Step 2
In a large saucepan scald the milk with the cream over moderate heat. In a large heatproof bowl whisk together the whole eggs, the egg yolks, and the remaining 3/4 cup sugar until the mixture is light and frothy. Add the scalded milk mixture in a slow stream, stirring constantly, and stir in the lemon juice, the zest, and the vanilla. Set the loaf pan in a larger and deeper baking pan and strain the custard mixture into the loaf pan. Cover the loaf pan with heavy-duty foil and add enough hot water to the larger pan to reach two thirds of the way up the sides of the loaf pan.
Step 3
Bake the custard in the middle of a preheated 325°F. oven for 1 hour and 20 minutes, remove the loaf pan from the baking pan carefully, and remove the foil. (The custard will not appear set in the middle but it will continue to cook as it cools.) Let the custard cool and chill it, overnight. Run a thin knife around the edge of the custard, invert a serving platter over the custard, and invert the custard onto it.
