Heat oven to 400°F. Roll out the bottom crust and line a pie plate with it.
To easily peel the peaches, gently lower them into a large pot of boiling water for 40-60 seconds, then remove to an ice water bath with a slotted spoon to shock them. After just a few seconds, the skin should slip off easily by just rubbing the peaches with your fingers. Remove pits and slice the peaches.
In a large bowl, combine the fresh, sliced peaches with the sugar, cornstarch, flour, cinnamon, allspice, salt, vanilla and lemon juice and toss to evenly coat the peaches.
6-7 large ripe peaches, 1/2 cup sugar, 3 Tablespoons cornstarch, 2 Tablespoons all-purpose flour, 1/2 teaspoon cinnamon, Pinch of allspice, 1/4 teaspoon salt, 1 teaspoon pure vanilla extract, 1 Tablespoon fresh lemon juice
Fill the bottom pie shell with the peach mixture, including the juices that will be released from the peaches. Dot with butter, then roll out the top pie crust and gently transfer it over the peach pie filling. Crimp the edges and cut a few slits in the top of the crust, then brush with the beaten egg and sprinkle with coarse sanding sugar.
2 Tablespoons salted butter, 1 egg, Coarse sanding sugar
Place pie on a baking sheet and bake in oven for 45-50 minutes, until the filling is bubbling and the crust is nicely browned. You may need to cover the edges with foil during the last 15-20 minutes of baking to prevent them from getting too brown.
Remove the pie from the oven and cool for at least 3 hours before cutting into it. Serve with vanilla ice cream.