Whatever radius you calculate is best for your piece, you'll find this two-flavor Pi Day pie is perfectly delicious, mathematically speaking.
10 to 12 servings
For the crust:
1 1/2 cups all-purpose flour
1 cup rye flour
1 tablespoon sugar
1/2 teaspoon kosher salt
2 sticks unsalted butter, cubed and chilled
6 tablespoons ice water
2 cups cherry pie filling
3 cups apple pie filling
Grease a 9-inch deep-dish pie pan and set aside.
In the bowl of a food processor fitted with the blade attachment, place flours, sugar and salt and pulse to combine.
Add butter to the processor and pulse until the mixture resembles a coarse meal. With the processor running, slowly drizzle in up to 6 tablespoons of ice water until the mixture comes together and begins to form a ball.
Knead the dough a few times by hand if necessary, then flatten into two disks and wrap in plastic wrap. Refrigerate for at least one hour.
Preheat oven to 400 degrees. Roll the dough out on a floured surface to about 1/4 inch thick. Roll out one crust to the size of the prepared pie pan and place it in the bottom. Crimp the edges.
Cut a 2-inch-wide strip of pie crust and create the shape of the Pi symbol. Freeze the dough for 30 minutes.
Fill the interior of the Pi with cherry filling and the exterior with apple pie filling. Bake for about 15 minutes, then lower the oven temperature to 375 degrees and bake for another 30 minutes or until the entire pie is bubbling. Allow to cool for 20 minutes, then serve.