Here's my entry for the Pi Day Pie contest, adapted from a blackberry cobbler (Thanks Nancie!). Please enjoy as irresponsibly as you see fit. =)
Step 1: Ingredients and Middle Crust
Pastry for 9-inch double-crust pie (store bought or hand made)
1 cup sugar
2 tbs all-purpose flour
2 tsp vanilla extract
1/4 cup cold water
1 lb blackberries
1/2 lb raspberries
2 tbs cold butter, chopped into small pieces
Heat the oven to 450F.
Roll out a third of the dough and trim it to make a 9-inch square. Place it on an aluminum foil-lined baking sheet, and place in the oven until the square is lightly browned, about 10 minutes. Set aside to cool. Leave the oven on.
Step 2: Bottom's Up
Roll out another third of dough into a 10 or 11-inch square, and fit into a 8 or 9-inch square baking pan. Be sure to cover the surface of the baking pan, and leave a small overhang. Save the dough scraps for use on the top crust.
Step 3: Gimme Some Sugar
Combine the sugar and flour in a small bowl. Stir the vanilla into the water. Set along side the pie with the berries.
Step 4: Makin' Pi
With roughly half the raspberries, lay out the shape of Pi in the pan. Fill in the pan with blackberries. The berries should not cover the bottom completely.
Step 5: Sweetness
Sprinkle half the sugar mixture over the berries, then sprinkle half the water over the sugared berries. Finally, scatter half the butter chunks over, you guessed it, the berries.
Place the baked pie crust square on top of the berries.
Step 6: Do It All Over Again
Place the remaining berries in the pan, making a square in the lower left corner with the raspberries. Sprinkle the remaining sugar, vanilla mixture, and butter over the berries, adding a little extra water for coverage if necessary.
Step 7: Top It Off
Roll out the remaining dough and scraps into a circle with a diameter equal to the width of the pan. Cut out a 'Pi' symbol in the top half. Cut off the the lower left quadrant ( between 6 and 9 o'clock). Finally, cut out a lower case 'r' near the vertical line.
Lay the dough on top of the pie, pressing the top crust together with the overhang from the bottom crust.
Step 8: 'That Pi(e) R Squared!'
Place on a baking sheet to catch spills, and place on the bottom rack of the oven. Bake for 10 minutes, then reduce heat to 350F. Bake until the juice is bubbling and the crust is golden, 45-50 minutes more.
Place pie on a cooling rack and let cool for 20 minutes. You now have a pie that is both delicious and educational. Serve warm or at room temperature.