Today, 3/14*, has been named Pi Day: 3.14. As you learned in high school geometry, the Greek symbol is used in mathematics to represent the ratio of the circumference of a circle to its diameter, a constant which begins with 3.14159.
Pi Day was founded by physicist Larry Shaw in 1988; a non-binding resolution acknowledging it was passed by the United States House of Representatives In 2009.
Pi day started as an event at the San Francisco Exploratorium, where Shaw worked as a physicist.
On that first day, both staff and public marched around one of its circular spaces, and then at fruit pie. The Exploratorium continues to hold Pi Day celebrations, and the tradition expanded across countries that use the month-day format*—because who doesn’t want an excuse to eat pie?
(If you don’t like sweet pie, have a pizza pie.)
Some bakers make a pastry cut-out of the pi symbol to decorate the top crust. This ambitious baker not only did that, but added cut-outs of the first 31 digits of pi to the rim of the pi.
Here’s more about Pi Day.
Today we present a Key Lime Pie by Audra, The Baker Chick. Key limes are a sweeter, less acidic lime from the Florida Keys. They are also grown in Mexico, so are also called Mexican limes.
Audra adds two touches that create a more complex recipe. First, she uses salted butter instead of sweet in the crust, contributing to the salty-sweet pairing that has become so popular.
Next, she adds some sour cream to the filling, adding more dimension than the provided by the sweetened condensed milk alone. We love Audra’s recipes!
This is a quick recipe to make: just 25 minutes until it emerges from the oven. Prep time is 10 minutes, cook time is 15 minutes.
Ingredients For 1 Nine-Inch Pie
For The Crust
1. PREHEAT oven to 350°F.
2. COMBINE the graham cracker crumbs, melted butter, and the pinch of salt in a medium bowl. Mix together with a spoon and press into the bottom and up the sides of a 9 inch pie plate. Bake the crust for 5-7 minutes or until toasty around the edges.
3. MAKE the filling. Mix together the sweetened condensed milk, sour cream and lime juice. Pour into pie crust and bake for 10-12 minutes, or until little bubbles form on the surface of the pie and start to pop. Don’t let the pie get brown!
4. REMOVE from the oven, cool, and then allow the pie to chill for a few hours or overnight. When ready to serve…
5. BEAT heavy cream and powdered sugar to stiff peaks. Spoon over the pie and garnish with the lime zest.
*Many countries use the day-month format instead, i.e., today would be 14/3 instead of 3/14. March 14th is also Albert Einstein’s birthday.
†If you can’t find Key limes, use regular limes. Some people use bottled lime juice, but that’s the difference between fresh-squeezed and bottled orange juice. Key limes are less acidic, but that isn’t a huge factor in the outcome.