Classic Key Lime Pie
For the pastry:
- 1 1/4 cups all-purpose flour
- 1/4 tsp. salt
- 1 tsp. sugar
- 6 Tbs. (3/4 stick) cold unsalted butter, cut into
- 1/4 cup shortening
- 2 to 3 Tbs. ice water, or as needed
For the lime curd:
- 3 eggs
- 5 egg yolks
- 1/2 cup sugar
- 3 Tbs. milk
- Pinch of salt
- 1/2 cup Key lime juice
- 8 Tbs. (1 stick) softened unsalted butter, cut
into 1-inch pieces
For the meringue:
- 4 egg whites
- 1/2 tsp. vanilla extract
- 1/4 tsp. cream of tartar
- 1/3 cup sugar
To make the lime curd, in the top pan of a double boiler or in a nonreactive saucepan, whisk together the eggs, egg yolks, sugar, milk and salt until blended. Then whisk in the Key lime juice. Set the top pan over but not touching simmering water in the bottom pan, or set the saucepan over medium-low heat. (If using a saucepan, take care not to heat the mixture too quickly.) Cook, stirring constantly with a wooden spatula or spoon, until the mixture is warmed through, 1 to 2 minutes.
Begin adding the butter a little at a time, stirring each addition until blended before adding more. Continue cooking, stirring constantly and scraping the bottom of the pan, until a finger drawn across the back of the spatula leaves a path, 8 to 10 minutes more. Immediately remove the pan from the heat. Pass the curd through a chinois set over a nonreactive bowl and let cool to room temperature.
Position a rack in the center of an oven and preheat to 425°F.
On a lightly floured surface, roll out the pastry into a 12-inch round, about 1/8 inch thick. Transfer the dough to a 9-inch pie dish, fit the dough into the dish and trim the edges, leaving a 1/2-inch overhang. Fold under the excess dough and, using your thumb, decoratively flute the edges.
Line the bottom of the pie shell with parchment paper and fill the center with pie weights or dried beans. Bake for 12 minutes, then remove the parchment paper and weights. Continue baking until the pastry is golden and flaky, 10 to 12 minutes more. Transfer the pie dish to a wire rack and let cool for 5 minutes.
Reduce the heat to 350°F. Pour the curd into the pie shell. Bake until the curd is set around the edges but still a little loose in the center, 20 to 25 minutes.
Meanwhile, make the meringue: In the bowl of an electric mixer fitted with the whisk attachment, beat the egg whites, vanilla and cream of tartar on medium speed until soft peaks form, about 1 minute. Increase the speed to high, add the sugar 1 Tbs. at a time, and beat until stiff, glossy peaks form, about 4 minutes more.
Spread the meringue over the hot filling to the edges of the pastry. Bake until the top is golden, about 15 minutes. Transfer the pie to a wire rack and let cool to room temperature. Refrigerate for at least 4 hours before serving. Dip a knife in hot water to cut slices.