To prepare crust, whisk together the flour, sugar and salt in a large bowl.

Scatter the butter and shortening over the dry ingredients, and cut in with a pastry cutter until the large clumps of the butter are broken up.

Drizzle half of the water over the flour mixture and lightly mix with a fork, until the dough starts to form clumps.

Using your hands, form the pastry into two balls – one slightly larger for the bottom crust.

Knead each ball once or twice on a floured work surface, then flatten the balls into ¾-inch-thick disks.

Wrap the disks in plastic, and refrigerate for at least an hour or overnight before rolling.

On a sheet of lightly floured wax paper, roll the larger portion of the pastry into a 12-inch circle.

Invert the pastry over a 9-inch standard pie pan center, and peel off the paper.

Gently tuck the pastry into the pan, without stretching it, and let the overhang drape over the edge.

Place in the refrigerator for 15 minutes.

Preheat the oven to 400 degrees F.

Split the vanilla bean lengthwise. Scrape the seeds out of the bean, and place them in a food processor.

Add the sugar, and process for about 1 minute until no large clumps of the vanilla bean remain.

Transfer the sugar to a small bowl. Mix ½ cup of the sugar with the cornstarch in another bowl. Set aside.

In a separate, large bowl, combine the peaches, cornstarch mixture, and lemon juice. Set aside.

On another sheet of floured waxed paper, roll the other half of the pastry into a 10-inch circle.

Dump the filling into the chilled pie shell, leveling the top with a spoon.

Dot the top of the fruit with the butter.

Lightly moisten the rim of the pie shell.

Invert the top pastry over the filling, center, and peel off the paper.

Press the top and bottom pastries together along the dampened edge.

Using the back of a butter knife, trim the pastry flush with the edge of the pan.

Cut several steam vents in the pie with a fork or paring knife.

Place the pie on the center oven rack, slide a large baking sheet onto the rack below to catch any spills, and bake for 30 minutes.

Reduce the oven temperature to 375 degrees F, and rotate the pie to ensure even cooking.

Continue to bake until the top is a deep golden brown and the juices visible at the side vents bubble thickly, about 30 minutes.

Transfer the pie to a wire rack, and immediately sprinkle half the remaining vanilla sugar (about ¼ cup) over the top.

Let it cool for at least 2 hours.

Shortly before serving, whip the cream with an electric mixer until it holds soft peaks.

Add the remaining vanilla sugar, and beat until stiff but not grainy.

Serve a large dollop of whipped cream with each slice of pie.