Preheat oven to 350°F Coat a 9-inch pie pan with cooking spray.
To prepare crust: Stir flour, 1/2 cup sugar and 1/4 teaspoon salt in a medium bowl. Stir in oil and butter with a fork until well blended and crumbly (it should look like wet sand). Using the back of a spoon, firmly press the dough into the bottom and up the sides of the prepared pan. Bake the crust until it just begins to brown, about 20 minutes. (Keep the oven on for Step 4.).
To prepare filling: Meanwhile, combine cranberries and orange juice in a medium saucepan. Bring to a boil over high heat and cook, stirring occasionally, until all the cranberries are beginning to break down, 5 to 6 minutes. Pour through a fine-mesh sieve into a medium bowl, pressing on the solids to extract all the juice. Whisk 3/4 cup sugar into the juice until combined. Whisk in whole egg and 3 egg yolks. Return the cranberry mixture to the saucepan and cook over medium heat, stirring constantly and vigorously, until it thickens and just starts to bubble as you are stirring, 4 to 5 minutes. Pour the warm filling into the warm crust. Set aside while you prepare the meringue topping.
To prepare topping: Beat the 3 egg whites in a large bowl with an electric mixer on medium speed until frothy. Add cream of tartar and pinch of salt and beat at high speed until soft peaks form. Very slowly add 1/3 cup sugar, beating constantly, until the mixture holds stiff, shiny peaks. Beat in vanilla. Spoon the meringue over the filling, then gently spread to the edges of the crust. Make peaks in the meringue with the back of a spoon or a small off-set spatula. Bake until the top is lightly browned, about 15 minutes. Cool the pie on a wire rack to room temperature, at least 3 hours, before serving.
TIPS & NOTES: Bake with white whole-wheat flour, made from a special variety of white wheat, and whole-wheat pastry flour, milled from soft wheat and containing less gluten. Both provide the nutritional benefits of whole grains. Find them in large supermarkets, natural-foods stores and online at bobsredmill.com and kingarthurflour.com. Store in the freezer.