Buttermilk Pie
https://www.cookscountry.com/, APRIL/MAY 2013

Buttermilk is a baker’s secret—add it to just about anything for a moist, tender, tangy result. Now imagine how creamy and delicious it would be in a pie.

WHY THIS RECIPE WORKS

To put the tang back in this Southern dessert, we nearly doubled the amount of buttermilk called for in most recipes. A moderate hand with the sugar and a splash of white vinegar further accentuate the buttermilk flavor. To keep the texture silky, we found that cornstarch fared better than flour for thickening our filling, and plenty of egg yolks and heavy cream didn’t hurt either. To keep the pie from curdling in the oven, we bake it at a gentle 300 degrees, cranking the heat only at the end to create a crackly, crisp top.

Crust
1 (9-inch) single-crust pie dough
1 large egg white, lightly beaten

Filling
¾ cup sugar
1 tablespoon cornstarch
¾ teaspoon salt
2 eggs
5 egg yolks
1¾ cups buttermilk
¼ cup heavy cream
4 tablespoons unsalted butter, melted
2 teaspoons distilled white vinegar
1½ teaspoons vanilla extract
2 teaspoons cup granulated sugar

Make the Pie Crust:

Roll the dough into a 12-inch circle on a lightly floured surface. Transfer the dough to a pie plate and fold any overhanging dough underneath itself so the edge of the dough is flush with the outer edge of the pie plate. Crimp edges as desired.

Refrigerate the dough-lined pie plate for 40 minutes, then place in the freezer for 20 minutes. While the crust is in the freezer, adjust the oven racks to the upper-middle and lower-middle positions and preheat the oven to 375 degrees F.

Line the chilled pie plate with two pieces of parchment paper, allowing the parchment edges to hang over the edges of the pie crust. Fill the lined pie crust with pie weights, place on a lined baking sheet and bake on the lower-middle oven rack until lightly golden around the edges, 20 to 25 minutes.

Remove the parchment and pie weights, rotate the baking sheet and continue to bake until the crust is golden brown, 5 to 7 more minutes. Brush the surface of the hot crust with the egg white and bake for an additional 1 minute.

Make the Pie Filling:

While the crust is baking, prepare the pie filling. In a large bowl, whisk together ¾ cup of the sugar, the cornstarch and salt. Add the eggs and egg yolks and whisk to thoroughly combine. Add the buttermilk, heavy cream, melted butter, white vinegar and vanilla extract, and whisk until completely combined.

Once the crust is done, reduce the oven temperature to 300 degrees F. If the pie filling has been sitting for a few minutes, give it a short whisk to recombine, then transfer to a 4-cup measuring cup (or other large bowl/cup with a spout). Leaving the pie crust in the oven (just slide the oven rack out a bit), carefully pour the filling into the hot pie shell. Bake for 10 minutes.

Again, leaving the pie crust in the oven and just sliding the oven rack out, sprinkle the remaining 2 teaspoons of sugar evenly over the top of the pie. Continue to bake until the center jiggles very slightly when the pie is shaken, 30 to 40 minutes.

Remove the pie from the oven and increase the oven temperature to 450 degrees F. Once the oven comes to temperature, place the pie on the upper-middle rack and bake until the top is golden brown, 5 to 7 minutes.

Remove from the oven and place the pie plate on a wire rack and allow to cool for 30 minutes. Transfer the pie to the refrigerator and chill for at least 3 hours before serving.