Make the filling: In a medium saucepan, combine the blueberries, cranberries, sugar, cornstarch, and orange zest and juice and cook, stirring frequently until the mixture comes to a simmer. Let simmer for a few minutes until the liquid has thickened and a few berries are beginning to burst.

Transfer the berries to a shallow bowl and place them in the refrigerator to cool quickly and completely.

Once the filling is cooled, preheat the oven to 375°F (190°C).

On a floured surface, roll out one pie crust ¼-inch (6mm) thick and line the bottom of a 9-inch (23cm) pie plate with it. Pour in the cooled filling.

Roll out the second pie crust ¼-inch (6mm) thick and using a 1-inch (2½cm) cookie cutter of your choice, cut out shapes and arrange on top of the filling. If you want to arrange the cut-outs along the edge of the pie, brush the edge with egg wash to help to cut-outs stick.

Once you are done arranging your cut-out on the pie, brush with the egg wash and sprinkle with sugar.

Place the pie on a lined baking sheet to catch any drippings and bake for roughly 50-60 minutes, or until the crust is golden and the filling is bubbling. Let cool completely before serving. Store, loosely covered, at room temperature for up to 2 days.