Remove the prepared pie dough from the refrigerator and place on a lightly floured surface. Roll out the pastry to a large round, about 12-inches in diameter. Transfer to a 9-inch pie pan , trim the edges to within 1/2-inch of the pan, and crimp decoratively. Refrigerate for 20 to 30 minutes.
Preheat the oven to 400 degrees F.
Line the shell with parchment paper and fill with pie weights . Bake for 10 minutes. Remove the paper and bake until golden brown, 15 to 20 minutes. Remove from the oven and cool on a wire rack. In a small bowl, beat 1 egg white and brush over the bottom of the crust to seal.
Reduce the oven temperature to 325 degrees F.
Combine the whole eggs, 1 1/2 cups of the sugar and a pinch of salt in a large bowl and beat with an electric mixer until thick and pale. Beat in the cream, juice, butter, cornmeal , zest and nutmeg . Pour the filling into the pie shell and bake until the custard is just set, 35 to 40 minutes. Remove from the oven and leave the oven on.
While the pie is baking, make the meringue. In a large, clean bowl using clean beaters, beat the remaining 4 egg whites with the cream of tartar and a pinch of salt with an electric mixer until soft peaks form. Beating constantly, slowly add the remaining 1/2 cup sugar until glossy, stiff peaks form, being careful not to over beat, as this will make it difficult to spread. Using a rubber spatula , spread the meringue evenly over the pie filling, smoothing out to the pastry edges so the meringue won't draw up or weep during baking. With a dull knife make decorative peaks in the meringue. Bake until the meringue is golden, 14 to 15 minutes.
Transfer the pie to a wire rack to cool completely. Garnish the top of the pie with the white chocolate shavings, cut into wedges and serve.
/4 cups all-purpose flour 1 tablespoon sugar 1/4 teaspoon salt 6 tablespoons cold unsalted butter , cut into small pieces and chilled 2 tablespoons cold vegetable shortening 3 to 5 tablespoons ice water, as needed Sift the flour, sugar and salt into a large bowl. Add the butter and shortening. Rub the fats between your fingertips and thumbs, or use a pastry blender , until the mixture resembles coarse crumbs. One tablespoon at a time, work in enough ice water until the dough comes together, being careful not to overmix or the crust will be tough.
Shape into a smooth ball of dough, flatten into a disk, and wrap in plastic wrap . Refrigerate for at least 30 minutes, and up to 2 days.
Yield: 1 (9 or 10-inch) piecrust