This pie recipe is the perfect candidate to take to your Pi Day D&D or Mensa potluck. Though it does produce a respectably tasty pie in its own right, the true appeal is the way the spirit of pi thoroughly permeates this baked delight. At the macro level, this pie has three ingredients in the topping layer, one ingredient in the filling layer, and four ingredients in the crust layer. As you delve deeper, you find the ingredient measurements themselves display the glorious irrationality of this timeless constant. And finally, the shape of the pie itself cannot resist throwing in a last word.

Step 1: Ingredients, and Preheat

3 tablespoons flour
1 tablespoon butter
4 tablespoons brown sugar
1 cup flour
5/9 cup butter
2/6 cup water
.5 cup sugar
3/5 quart canned pie filling (any flavor)

Note: See step 7, Pro tips, for an easy conversion listing of the measurements.

Begin preheating your oven to 350 degrees Fahrenheit.

Step 2: Combine the Topping Ingredients, and Mix

Combine your three topping ingredients (3 tablespoons flour, 1 tablespoon butter, 4 tablespoons brown sugar) in a mixing bowl. Use a pastry cutter or approximate tool to cut everything together until it resembles coarse crumbs. Set aside.

Step 3: Combine the Crust Ingredients, and Mix

Combine your three non-liquid crust ingredients (1 cup flour, 5/9 cup butter, .5 cup sugar) in a mixing bowl. Use a pastry cutter or approximate tool to cut everything together until it resembles coarse crumbs. Add your fourth ingredient (2/6 cup water) and mix well until it becomes a ball of dough.

Step 4: Add Flour to Dough and Working Surfaces, and Roll Out

Add pinches of flour at a time to your dough ball as you knead it, until it no longer sticks easily to your hands. Liberally sprinkle your working surface with flour, and roll the dough ball out into a thin, flat crust.

Step 5: Assemble Your Pie, and Bake

Press your crust into your pie pan, trimming away excess as needed. Open your can of pie filling and pour it into the now-panned crust. Sprinkle the top of the filling with your topping mixture. Put your pie into your preheated oven and bake for about 30 minutes, or until the edges of the crust are turning a golden brown.

Step 6: Final Product

When the edges of your pie are turning golden brown, remove it from the oven and let it cool before serving. If, while in the oven, your pie happened to change shapes, don't worry. It is, of course, because pie are squared....

Step 7: Pro Tips

Easy conversion of ingredients:
3 tablespoons flour
1 tablespoon butter
4 tablespoons brown sugar
1 cup flour
4 1/2 tablespoons butter
1/3 cup water
1/2 cup sugar
1 20 ounce can pie filling (minus 0.8 ounces if you want to get precise)

Choice of pans:
I found that when I used a glass pan (not pictured) I had no problem with the crust being cooked all the way through. A metal pan resulted in a crust which needed a little extra TLC. I would recommend just using a glass pan.

Pi symbol:
I cut a pi symbol out of waxed paper, and laid it on top of the filling prior to adding any topping. Then I sprinkled the topping all over the pie, and brushed the filling away from the waxed paper. Then I pulled the wax paper off of the pie, leaving a filling-free symbol.