ABOUT 40 MINUTES BEFORE SERVING OR EARLY IN DAY:.
Preheat oven to 425°F Grease cookie sheet.
In bowl with fork, mix flour, baking powder, 2 teaspoons sugar, and 3/4 teaspoon salt. Cut in butter or margarine until mixture resembles coarse crumbs. In measuring cup, beat egg; reserve 1 tablespoon egg for brushing on crust. Add milk to egg in cup to make 1/2 cup. Stir egg mixture into flour mixture just until blended.
On cookie sheet, pat out dough about 1/2-inch thick and 3 inches smaller than top of 2-quart shallow casserole (fruit will show around edge). With tip of soup spoon, make decorative scalloped design on top (pressing deeply so the impression won't disappear as crust rises); brush with reserved egg; sprinkle with sugar. Bake crust 15 minutes or until golden; remove to wire rack.
Meanwhile, prepare filling:.
Drain syrup from peaches into measuring cup. In 3 quart saucepan, mix tapioca, 3/4 cup sugar, 1/2 cup peach srup, and 1/4 teaspoon falt; let stand 5 minutes. Add rhubarb; cook over medium heat until rhubarb is tender and mixture thickens and boils, stirring often. Stir in peaches and prunes; heat through. Pour mixture into casserole; top with crust.
Serve cobbler warm. Or, cool to serve later. To serve, prepare Brandied Cream; pass to spoon over each serving. Makes 10 servings.
To Make Brandied Cream:.
In small bowl with mixer at medium speed, beat heavy cream with 1 tablespoon sugar to soft peaks. Beat in 1 tablespoon brandy.