Introduction: Pi Within a Pie

About: I bake to combat stress. I'm in grad school -- there's a lot of stress and a LOT of baking.

I love baking.  I love math.  I love Pi Day!  When cooking/baking, I usually just try to make it taste good, but this year I wanted to make something that looked cool and tasted great.  I was inspired by the recent “cookie within a cookie” brilliance, and I decided that I needed to figure out how to put π into a pie.  

Step 1:

While brainstorming, this is the exact image that popped into my head….I just needed to find a way to make it happen!  I settled on a peanut butter pie with a chocolate π ring almost immediately.  I thought it would be relatively easy to dig trenches in the pie, and chocolate ganache seemed like an ideal filling.  First up: crust!

Step 2:

I used SmittenKitchen’s crust recipe as a guide (from the Brownie Mosaic Cheesecake, which is amazing!

8 ounces chocolate flavored animal graham crackers, finely ground

8 tablespoons unsalted butter, melted

1/2 cup sugar

1/8 teaspoon salt


1.  Preheat oven to 350. 

2.  Add chocolate graham crackers, sugar, and salt to bowl of food processor; process until fine. 

3.  While the food processor is running, drizzle in the melted butter. 

4.  Once you have a uniform mixture, dump the mixture into a 9-inch pie plate. 

Step 3:

Spread the crust mixture evenly across the bottom and up the sides of the pie plate, using the bottom of a measuring cup to press it in.  I tried to make the edge look pretty by using my finger to stop the crust from going too far up. 

Once you’re happy with your crust, bake it for ~8 minutes at 350.   Allow to cool.

Step 4:

I used The Pioneer Woman’s recipe for chocolate peanut butter pie.
She uses an Oreo crust – I’m sure it’s delicious, but I wanted something lighter.

1 cup creamy peanut butter

8 ounces cream cheese, softened

1 ¼ cup powdered sugar

8 ounces Cool Whip, thawed (I would have tried to substitute whipped cream, but she insisted that you use Cool Whip in order to achieve the proper texture.  I listened.)

Step 5:

Beat the peanut butter and cream cheese together until smooth.  Add the powdered sugar, and beat until smooth.  Add ~1 cup of Cool Whip, and beat until smooth.  Fold in the rest of the Cool Whip.

Step 6:

Add ~3/4 of the peanut butter mixture to the cooled pie crust; smooth the top, and try to make it as flat as possible.  Refrigerate the pie (and the remaining peanut butter mixture) for about an hour.

Step 7:

Once the pie firmed up a bit, I pressed the tops of a bowl (~5.5 inch diameter) and a ramekin (~4 inch diameter) into the top of the pie, making sure that they were centered.  These concentric circles would become the “legs” of my π. 

Step 8:

With my guides in place, I used various kitchen utensils to dig out my trenches (and added the filling to the remaining filling that was in the fridge).  The handle of this scoop worked pretty well, but I had to clean up the edges of the trenches with a knife.  Also, I tried to avoid digging all the way to the crust.   

Step 9:

The trenches ended up being a little under a centimeter wide – I knew that it would look better with skinnier trenches (legs), but during a trial run, I learned that it’s really hard to fill the skinny trenches.  So, wide trenches for me!

Step 10:

I then used a makeshift piping bag (filled with the leftover peanut butter filling) to add a circle to the middle of the pie (it's a little hard to see, but it's there!) and a peanut butter edge next to the crust.  These would act as dams and help create the top of the π. 

Once the trenches and dams were done, the pie went back into the refrigerator for 30 minutes or so – it softens really quickly!

Step 11:

Next up: ganache!

1/2 cup heavy cream

¾ cup chocolate chips

A handful of peanut butter chips

1.  Heat the cream just until it bubbles, and then add it to the chocolate and peanut butter chips. 
2.  Stir until melted and smooth, and allow to cool slightly.  I then filled my fancy squeeze bottle piping thing with the ganache and carefully filled the trenches. 

I would probably add more cream next time - a softer ganache would have been easier to cut. 

Step 12:

Rivers of chocolate ganache!

Step 13:

I then flooded the area above the trenches with more chocolate ganache (taking care not to go over the dams).  Again, it went back into the fridge for about 30 minutes.  I needed the ganache to be firm enough for me to spread the remaining peanut butter filling on top.

Step 14:

Once the ganache was firm, I spread the rest of the peanut butter filling over the top of the pie.  Here is where I should have stopped…..but I had extra ganache and decided to embellish the top of the pie. 

At this point, the pie went into the freezer until it was ready to be served -- I found that it was easiest to cut when frozen. 



Step 15:

The finished product!  As neat as this was, I would have considered it a total failure if the guests at my Pi Day party didn't eat it.  Luckily, it was delicious! 

Lessons learned:
1.  As I mentioned earlier, I would try to make a softer ganache next time - at room temperature, the peanut butter filling was way softer than the chocolate, making it impossible to neatly cut.
2.  The peanut butter filling was kind of sticky and softened quickly at room temperature.  Maybe a different pie would be easier to carve?  I also made a key lime pie -- that might have worked better, but I couldn't think of a filling.  Whipped cream, maybe?  

Thanks for reading!  :)
Serious Eats Pi Day Pie Contest

Second Prize in the
Serious Eats Pi Day Pie Contest