In a small bowl, whisk the sour cream and egg yolk to combine. Set aside.
In the work bowl of a food processor, pulse the flour, white sugar, and salt a few times to combine.
Add the butter to the bowl and pulse about 10 times, until butter is in pea size pieces. *Do not over mix.
Add half the sour cream and egg mixture and pulse about 5 times to combine, then add the remaining sour cream mixture and pulse/process to create a smooth, pliable dough.
Gather the dough together and transfer to a work surface. Separate the dough into two evenly sized balls. Wrap each separately in plastic wrap and chill in the refrigerator for 30 minutes.
In a large nonstick sauce pan over medium-high heat, stir together peaches, brown sugar, cornstarch, cinnamon, vanilla extract, and salt.When mixture comes to a gentle boil, reduce heat to low. Simmer over low heat for 15-25 minutes, stirring occasionally, until mixture thickens.
When the crust is completely cold and you’re ready to bake the pie, preheat oven to 350℉.
On a lightly floured work surface, use a rolling pin to roll one ball of pastry dough to a diameter of 10 inches. Gently lift the crust and place it in a 9-inch pie pan. Use kitchen shears or a sharp paring knife to trim excess dough from the edge.
Fill the crust with the peach filling. Repeat previous step to roll out the top crust.
Gently transfer the second pie crust over the filling, pressing gently so it lays flat against the filling. Flute the edges using your thumb and forefinger. Using a small paring knife, cut four slits in the center of the crust to allow for venting.
Bake in preheated oven for 35-45 minutes, checking at 35 minutes to ensure that the edges aren’t overbrowning. *If the edges of the crust are getting too brown, cover them with a pie crust shield or strips of aluminum foil.
The pie is finished baking when the crust is golden brown and the filling is bubbling and set. Remove from oven and transfer to a wire cooling rack to cool for at least 2 hours before slicing.
Notes
Be sure the pie crust ingredients are very cold, especially the butter.
If you don't have a food processor, you can use a pastry cutter to make the pie dough.
Want a double crust pie with streusel topping? My cranberry pie recipe lists the ingredients and instructions for making streusel topping.
Best peaches: Freestone peaches are typically the best for baking because the pit is easiest to remove. To make peach pie with frozen peaches, be sure to thaw them before you make the filling.