for the Pie Dough
2 1/2 cups all purpose flour
1 tablespoon sugar
3/4 teaspoon salt
10 tablespoons (1 1/4 sticks) chilled unsalted butter, cut into 1/2-inch pieces
1/3 cup chilled solid vegetable shortening, diced
6 tablespoons (or more) ice water
for the filling
2 red plums , halved and pitted
6 cups (about 2 pounds) pitted sweet cherries or 6 cups pitted frozen cherries, halved
1/2 cup sugar (3 1/2 ounces)
1/8 teaspoon table salt
1 tablespoon juice from 1 lemon
2 teaspoons bourbon (optional)
2 tablespoons instant tapioca , ground in a coffee grinder
1/8 teaspoon ground cinnamon (optional)
2 tablespoons unsalted butter , cut into 1/4-inch pieces
1 large egg , lightly beaten with 1 teaspoon water
1 tablespoon powdered sugar (optional)
Blend flour, sugar and salt in processor. Add butter and shortening and cut in using on/off turns until mixture resembles coarse meal. Add 6 tablespoons ice water and process until moist clumps form, adding more water by teaspoonfuls if
dough is dry. Gather into ball; divide into 2 pieces. Flatten each into disk. Wrap each in plastic; chill 2 hours.
Preheat oven to 400F.
Roll out 1 dough disk on floured surface to 13 inch diameter circle. Transfer to 9-inch-diameter glass pie dish. Fold edge under, forming high-standing rim; crimp. Chill in freezer for 15 minutes.
For the filling, process plums and 1 cup halved cherries in food processor until smooth, about 1 minute. Strain puree through fine-mesh strainer into large bowl, pressing on solids to extract liquid; discard solids. Stir remaining halved
cherries, sugar, salt, lemon juice, bourbon (if using), tapioca, and cinnamon (if using) into puree; let stand for 15 minutes.
Transfer cherry mixture, including all juices, to dough-lined plate. Scatter butter pieces over fruit. Roll second disk of dough on generously floured work surface and using a snowflake cookie cutter, cut out as many snowflakes as you
can. Place over pie, creating an almost full top-crust, but leaving some small vents. Freeze pie for another 20 minutes.
Bake 30 minutes at 400F. Reduce oven temperature to 350F and continue to bake until juices bubble around the edges and crust is deep golden brown, 30 to 40 minutes longer.
Transfer pie to wire rack; let cool to room temperature so juices have time to thicken, 2 to 3 hours. Dust with powdered sugar (optional). Cut into wedges and serve.