Mathematics nerds and schoolchildren alike will be celebrating Pi Day, March 14, 3.14. Pi is the ratio of a circle’s circumference to its diameter.
Consequently, one can use pi to calculate the area of a circle by multiplying pi by the radius squared.
The concept of pi, usually represented by the Greek letter π, is one of the mysterious and marvelous wonders of mathematics. To read about π is to be utterly astonished: the numerical ratio of that circumference to the diameter never ends. In other words, it is actually 3.141592653589……ad infinitum (FOREVER)—not just 3.14. All this and with no pattern to the repeating decimal digits!
Many of us are stymied and confused by the wonders of mathematics, but I urge you to sit back and ponder a creation of such astonishing beauty. Mathematics is one of those wonderous parts of our world that is hidden in plain sight.
But let’s talk about pie.
We always celebrate March 14 with a pie. So, I’ve been thinking about fruit pie, chocolate pie, and all sorts of pie. Last month I made a cherry pie for Washington’s birthday. I decided to use goose fat that I had saved from Christmas for the crust. It was a disaster, so I will not be recommending goose fat for pie crust, although it makes fantastic biscuits.
For this year’s Pi Day I will be making banana cream pie. Bananas and cream are always available, so I deem this “seasonal” for March. I adapted this recipe from my mother’s American Woman’s Cookbook, first published in 1938.
Banana Cream Pie
For the crust:
- 1 ½ cups flour
- ¾ tsp salt
- ½ cup chilled butter (one stick)
- 3 T ice water (or enough to bring the dough together)
For the filling:
- 1 ½ cup milk
- ¼ cup sugar
- ¼ tsp salt
- 3 T. flour
- 1 egg yolk
- 1 T butter
- ½ tsp vanilla
- 2-3 bananas
- 1 cup whipping cream
Preheat oven to 450°F. Mix the flour and salt. Add the butter and blend with a pastry blender, or two knifes, or your hands, until the butter is well distributed into the flour and is the size of small peas. Add the ice water and mix with a fork until the dough comes together.
Roll the dough on a flour covered surface, into a 10-inch circle (radius of 5 inches). Roll the dough onto the rolling pin and carefully place it into a 9-inch pie pan (radius of 4.5 inches). Press the dough onto the surface of the pan and then crimp the edges. Use a fork to pierce the dough in about eight places. Cover the dough with dry beans or pie weights. Bake for 8-10 minutes until lightly browned, and then allow to cool completely.
Pour 1 cup of the milk into a heavy saucepan and warm gently. In a separate bowl, whisk the sugar, flour and ½ cup of milk. Stir the mixture into the warm milk and cook slowly until it thickens. In a small bowl, whisk the egg yolk and then whisk it into the thickened milk custard. Cook for one minute longer. Add the butter and vanilla and cook, continuing to stir until the butter melts. Remove from heat and allow to cool for 10 minutes.
Put a layer of sliced bananas in the cooled pie shell. Cover with custard. Continue with two more layers. Cool the pie, and top with whipped cream.
N.B. My nine-inch pie plate holds about 64 cubic inches of filling (assuming a one-inch-thick pie). This was determined by: 9-inch diameter = 4.5-inch radius. 4.52 X π X 1-inch height = 63.6 cubic inches of filling.
1 cup = 14.4 cubic inches, so 63.6 divided by 14.4 = 4.4 cups. And so, this, friends, is why most pie recipes require 4 cups of filling. The missing 0.4 cup allows for filling expansion and avoids bubbling over when baking fruit fillings. Voila!