- Preheat the oven to 375 degrees.
- In a large bowl, combine the blueberries, cranberries, 1½ cups of sugar, cornstarch, orange peel, orange juice, and vanilla. Pour the fruit mixture into an unbaked 9-inch pie crust, sprinkle with the slivered almonds, and dot with butter. Top the fruit with the top crust and crimp the edges to seal.
- Make 4 or 5 decorative cutouts or slits in the top of the crust to allow steam to escape. Brush the top of the pie with the milk, and then sprinkle evenly with 1 tablespoon of sugar.
- Place the pie on a baking sheet and bake for 1 hour or until the filling is hot and bubbly. Cover the pie with foil if the edges begin to brown too quickly. Cool completely on a wire rack before serving. Serve with whipped cream if desired.