Pulse flour, 1/2 teaspoon salt, and the granulated sugar in a food processor. Add butter, and pulse until mixture resembles coarse meal. With machine running, slowly add ice water until dough comes together. Shape into a disk. Wrap in plastic. Refrigerate for 30 minutes.
On a lightly floured surface, roll out dough to 1/8-inch thickness. Fit into an 8-inch pie dish, leaving a 1-inch overhang. Freeze for up to 30 minutes.
Preheat oven to 400 degrees. Simmer port and 1/2 cup brown sugar in a saucepan over medium heat until reduced to 1/2 cup, about 25 minutes. Transfer to a bowl. Add chile if desired. Cover, and let cool for 10 minutes.
Stir together remaining 3/4 cup brown sugar and teaspoon salt, the plums, cornstarch, cinnamon, and port syrup. Transfer to pie shell. Fold in overhang to form a crust; brush crust with cream, and sprinkle with sanding sugar. Bake for 30 minutes; reduce oven to 375 degrees. Bake until golden and center is bubbling, about 1 1/2 hours more. Let cool.