For the crust: In a large mixing bowl, combine the flours and the butter powder, if using. Add the shortening and using a pastry blender, cut in the shortening until it resembles coarse crumbs. Set aside. In a small bowl, beat together the egg, vinegar, salt, and water. Add egg mixture to the flour mixture and combine with a fork, just until the dough comes together. Do not over mix. Form dough into a disk, wrap in plastic, and chill for several hours or overnight.
Preheat oven to 400 degrees F.
For the filling, drain the thawed raspberries, reserving the juice in a measuring cup. Drain the cherries and add enough of the juice from the cherries to make 1 cup liquid total.
In a saucepan mix the sugar, cornstarch, and salt. Stir in the juice and add the cherries, and simmer over medium-low heat until filling is thick and clear, about 4 to 5 minutes. Remove from heat and stir in the butter. Very gently fold in the raspberries. Set aside.
Using a little more than 1/3 of the dough, roll it out between 2 pieces of plastic wrap to a size that will overlap the edge of a 9-inch glass pie dish. Fit dough in pie dish, trimming off excess.
Add the filling. Roll out the remaining dough to fit the top. Place the dough over the filling, cut off the excess, and crimp edges to seal the dough. Brush the top with milk and sprinkle with sugar. Cut 3 or 4 slits for steam vents.
Place on the bottom shelf of the oven. Bake for 10 minutes, and then move to the middle shelf, reduce the heat to 350 degrees F, and continue to bake until the crust is a golden brown, about 30 to 35 minutes more. Cool completely before cutting.
A viewer, who may not be a professional cook, provided this recipe. The Food Network Kitchens chefs have not tested this recipe and therefore, we cannot make representation as to the results.
*Cook's Note: Butter powder is available online and at some specialty baking stores.