You’ve never heard of Pi Day? I suppose I shouldn’t be surprised when people outside my nerdy circle don’t get it. If you remember from geometry, the constant pi = 3.14. It is the irrational number (with an infinite number of decimal places) representing the ratio of any circle’s circumference to its diameter. Today is March 14th (in other words, or numbers, 3-14, or Pi Day).

I have to admit that I forgot about Pi Day this year until my friend mentioned that her daughter had applied to my alma mater MIT. This year, MIT was notifying applicants whether or not they got in today, Pi Day, at 1:59. (To be more specific, pi = 3.14159). I think that is hilarious!

As I’ve said before, I’m happy to turn any day into a food holiday. Pi Day certainly calls for a pie. Honestly, I prefer making tarts to pies, but, today, that wasn’t going to pass muster.

I had Meyer lemons, so I decided to make Meyer Lemon Pie. This is my own invention, but it’s really just Key Lime Pie, with Meyer lemon juice instead of Key lime.

If you’re not familiar with Meyer lemons, you should get acquainted. They are from California. Compared with a regular lemon, the Meyer lemon is smaller and a bit rounder; the skin is smoother and has a slight orange tinge. They are very fragrant with a floral lemon flavor. They aren’t quite as tart as a lemon, but the flavor is definitely lemon. They are definitely worth trying when you are lucky enough to see them at the market.

This pie starts with an easy graham cracker crust. I usually do it the day before I’m going to bake the pie.

I think the real secret to this pie is how long you beat the egg yolks. I beat the egg yolks with an electric hand mixer for a full 5 minutes. The egg yolks transform from a deep yellow to a buttery yellow. It always surprises me that the color can change so much just by incorporating with air. The end result is a light, smooth, and creamy pie.

Meyer Lemon Pie
Serves 8

1 9-inch graham cracker crust (see recipe below)
4 large egg yolks
1 can (14 oz) sweetened condensed milk
½ cup Meyer lemon juice (from 3-4 lemons)
½ tsp Meyer lemon zest

Preheat the oven to 350F. Beat the egg yolks with an electric mixer at medium speed for 5 minutes, until they are light yellow in color. Add the milk, juice, and zest, and beat until well blended.

Pour the filling in the crust. Bake until the filling is set, but still creamy, about 15 minutes.

Cool the pie completely on a rack. Then cover and chill for at least 4 hours before serving. Use foil, instead of plastic wrap, because the plastic wrap tends to sag and stick to the top of the pie.

For a Key lime pie, substitute Key lime juice (I use bottled) for the Meyer lemon juice and omit the zest.

Graham Cracker Crust
Makes 1 9-inch crust

1¼ cup graham cracker crumbs (I use the low-fat crackers)
2 Tbsp sugar
1/3 cup butter, melted

Preheat the oven to 350F.

Combine the crumbs and sugar in a small bowl. Add the melted butter, and stir together with a fork until it is mixed well.

Press the mixture evenly over the bottom and sides of a 9-inch pie plate. Bake for 8 minutes. Cool completely on a rack.