Stirring lemon juice into the cooked filling will not curdle the milk, as you might think it would. To the contrary, it results in a pie with a softly set consistency, creamier and richer than lemon meringue, with a smooth citrus flavor.
Makes one 9-inch pie
Crumb Crust for a 9-inch pie shell, made with gingersnaps or graham crackers (page 32)
1 cup sugar
¼ cup cornstarch
¼ teaspoon salt
2½ cups milk or evaporated milk
4 egg yolks
¼ cup (½ stick) unsalted butter, at room temperature
½ cup fresh lemon juice
1 tablespoon grated lemon zest
Whipped Cream (page 39)
Form and bake the crumb crust as directed in the recipe. Cool completely before filling.
Whisk together the sugar, cornstarch, and salt in a medium saucepan. Pour in the milk and whisk until smooth. Cook over moderate heat, whisking almost constantly, until the mixture thickens and comes to a boil. Boil gently for about 2 minutes, whisking constantly. Remove from the heat and add the egg yolks, whisking until blended. Bring the mixture back to a boil, then reduce the heat and cook for 2 minutes more, whisking constantly. Remove from the heat and add the butter, lemon juice, and lemon zest, stirring or whisking until the filling is smooth. Set aside to cool for about 10 minutes, stirring once or twice.
Pour the filling into the prepared crust. Refrigerate for at least 3 hours, until the filling is chilled and firm.
Before serving, prepare the whipped cream and spread it over the pie.