# Making Pies For Pi Day: Think Inside The Circle

Claire O'Neill/NPR

Editor's note: A version of this story was published in March 2011.

Get ready to roll out some dough, because it's almost Pi Day.

What's that, you ask? Think back to geometry class. Pi represents the ratio of a circle's circumference (the distance around the circle) to its diameter (the distance across it). In mathematics, it's been represented by the Greek letter "π" since the 1700s.

For the math challenged, think of something that's round. Might I suggest ... pie? It's the perfect example because, in addition to being round, it's pronounced the same way as pi. And you can even use pies to calculate Pi, more or less, as this video shows:

Now, it's been a long time since I sat in math class and learned about pi. Here's what I remember: The value of pi is about 3.14159. (The value of pie, on the other hand, is, of course, deliciousness.) Pi is often shortened further to 3.14, but it actually goes on forever.

Some genius grasped the idea before I did and started Pi Day — which, of course, is celebrated with pie.

But when to celebrate it? Well, the number 3.14, in terms of the calendar, translates to the third month and the 14th day — which means March 14. It's been further suggested that 1:59 is the perfect time to celebrate, reflecting a few more places after the decimal.

Pi plates, T-shirts and other retail items are helping Pi Day supporters take their math-themed celebration mainstream. Doreen McCallister/NPR hide caption

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Doreen McCallister/NPR

While I'm still a little bummed that I didn't come up with Pi Day, I have jumped on this holiday bandwagon. There are mathematics competitions, pi jewelry-making lessons and — no surprise here — pie-eating contests. I even participated one year in a Pi Fun Run. (And by "participate," I mean I walked; apparently pie isn't the breakfast of champions.)

Businesses that promote math, science and technology offer promotional Pi Day discounts. You can buy pi pie plates and clever pi T-shirts.

With all of those marketers on board, it's just a matter of time before we all — not just math enthusiasts — celebrate the day. I choose to believe that Pi Day is just overshadowed by St. Patrick's Day. I mean, come on — if you can count clover leaves, you can slice up a pie without any problem. Yes, pie — if not pi — really is easy.

Don't believe me? Try it out for yourself with some of my favorite recipes below — including one that elevates mincemeat pie to the 10th power.

Doreen McCallister is a senior editor for NPR. For more than 24 years, she's been keeping her NPR colleagues guessing about her baking experiments. Prod her on the secret ingredient in her extra-moist, scrumptious baked goods, and you're liable to get an answer like mayonnaise, tomato soup or even Velveeta. Even when she brings something "normal" to work, everyone demands to know: "What's in it? No, really — what's in it?" Whatever the secret, it's always delicious.

# Sweet Potato Pie

I had never eaten sweet potato pie, let alone made it, when a work colleague asked me to make one. The woman was insistent that I could make a good sweet potato pie. "Alright," I told her, "give me a week." One thing I learned through trial and error is that while pumpkin and sweet potato pies may look similar, they are very different. I went into the experiment thinking pumpkin pie would be my favorite of the two. Now, I'm not so sure.

Claire O'Neill/NPR
Claire O'Neill/NPR

Makes 1 9-inch pie

1 9-inch pie crust (make your own or use a store-bought refrigerated variety)

Nonstick cooking spray

3 cups cooked yams (fresh or canned)

4 tablespoons melted margarine

3 eggs

1/2 cup sugar

2 teaspoons cinnamon

1/2 teaspoon nutmeg

3/4 cup evaporated milk

1 teaspoon vanilla

1/4 cup chopped pecans (optional)

Preheat oven to 375 degrees.

Coat a 9-inch pie pan with nonstick cooking spray and place rolled-out dough in pan, crimping the edges and pricking the bottom with a fork.

Drain and mash yams. Mix in margarine, eggs, sugar, cinnamon and nutmeg. Then add evaporated milk and vanilla.

Pour mixture into shell. Sprinkle with pecans if desired. Sprinkle top with cinnamon and nutmeg.

Bake for 45 to 55 minutes. It's done when it no longer jiggles.

# Pizza Pie

Tired of regular pizza? This pie recipe is a chance to switch things up a bit. Use any ingredients you like; switch out the meat ingredients, if you prefer vegetables.

Claire O'Neill/NPR
Claire O'Neill/NPR

Makes 1 9-inch pie

2 9-inch pie crusts (make your own or use a store-bought refrigerated variety)

Nonstick cooking spray

1 pound hot sausage, cooked and drained

8 ounces mushrooms, sauteed

1/2 cup white onion, sauteed

1/2 cup red onion, sauteed

2 ounces pepperoni

4 slices Canadian bacon

1/2 cup Sweet Pepper Strips (a jarred condiment sold in major supermarkets), to taste

8 ounces mozzarella cheese, shredded

15 ounces of canned pizza sauce (as is, or add spices to taste)

4 ounces parmesan cheese, grated or shredded

Preheat the oven to 400 degrees.

Coat a 9-inch pie pan with nonstick cooking spray and place rolled-out dough in pan, pricking the bottom with a fork.

Begin adding sausage, mushrooms, onions, pepperoni, Canadian bacon, peppers and mozzarella cheese. Pour the sauce over the top, then sprinkle on the parmesan cheese. Place the second rolled-out crust onto the top of the pie, crimp the edges of the two crusts together, and cut some small vent holes in the top.

Bake for 15 minutes at 400 degrees. Lower oven temperature to 375 and bake for another 30 minutes.

Let rest for about 5 minutes before serving.

# Granola Cranberry Walnut Pie

This pie can be made lickety-split. It's perfect for after a heavy meal because it tastes lighter than a lot of berry pies (though it's not light calorically). Don't have time to make the granola crust? Use a store-bought graham-cracker crust. It's not as tasty but will do the trick.

Claire O'Neill/NPR
Claire O'Neill/NPR

Makes 1 9-inch pie

3 cups granola (homemade or use your favorite store-bought version)

1/3 cup melted butter

Nonstick cooking spray

14-ounce can of whole berry cranberry sauce

8-ounce tub frozen dessert topping, defrosted

1 cup walnuts, coarsely chopped

2 tablespoons fruit preserves

Preheat oven to 350 degrees.

Combine granola and melted butter in a small bowl. Coat a 9-inch pie pan with nonstick spray, then press the granola mixture into the pan.

Bake the crust for about 7 minutes at 350. Let cool for 15 minutes.

In a separate bowl, gently combine the cranberry sauce and whipped topping. Spoon the mixture onto the crust, then sprinkle on the walnuts.

Refrigerate for at least two hours. Before serving, garnish the pie with 1 to 2 tablespoons of fruit preserves (or more to taste).

# Pimp My Mince Pie

Long after the December and New Year's holidays are over, I usually remember that I have forgotten to make mince pie. Apparently I'm the only one who notices. An unscientific poll of my co-workers indicates that most of them don't like mince pie. I set out to remedy that, borrowing an idea from the MTV show Pimp My Ride. (If you haven't seen the show, they take a car that's in poor condition and restore it and customize it.) One suggestion: Don't tell people it's mince pie, and they will love it.

Claire O'Neill/NPR
Claire O'Neill/NPR

Makes 1 9-inch pie

1 9-inch pie crust (make your own or use a store-bought refrigerated variety)

Nonstick cooking spray

3 eggs

1/2 cup sugar

1 cup corn syrup (dark or light)

1/4 cup melted butter

1/2 teaspoon salt

1 cup chopped pecans

2 cups mincemeat pie filling (You can use store-bought filling or try this recipe from America's Test Kitchen)

21-ounce can of apple pie filling

1 cup walnuts

Preheat oven to 350 degrees.

Coat a 9-inch pie pan with nonstick cooking spray and place rolled-out dough in the pan, crimping the edges and pricking the bottom with a fork.

Beat eggs, sugar, syrup, melted butter and salt.

Stir in pecans, and pour into pie shell.

Bake 30 minutes.

Remove from oven and spread a layer of mincemeat pie filling on top of pecan layer. Spoon apple pie filling onto mince layer and spread evenly. Break up walnuts and sprinkle on top of apple layer.

Bake for another 30 minutes.