I decided to make a square pie because pi r^2... (pi are squared)

This pie involves white chocolate mousse, dark chocolate mousse and dark chocolate ganache.

You can you your own recipes for those items if you wish, but I've included the ingredients and method in these steps.

Step 1: Crust

REQUIRED: 200g chocolate cookie wafers, 1/2 cup butter, melted

Place cookie wafers in a food processor.

Process the wafers until they are crumbs and with the motor running, slowly add about 1/2 cup of melted butter.

When the crumbs stay together when pinched, they're ready.

Pour out crumbs into 9" square pan and press onto bottom and up sides.

Set aside.

Step 2: White Chocolate Mousse

INGREDIENTS:
12 oz quality white chocolate
1 packet (7 grams) gelatin
2 1/2 cups heavy whipping cream

Dissolve gelatin in 1/4 cup cold water, and set aside for 5 minutes.

Place chocolate in the bowl of a food processor, and pulse until very finely chopped.

Step 3: White Chocolate Mousse

Prepare an ice-water bath; set aside.

Place 3/4 cup cream in a small saucepan, and bring just to a boil over medium-high heat. Add gelatin, and stir for 30 seconds to dissolve completely.

Pour into food processor with the motor running, and process until chocolate mixture is smooth.

Transfer to a medium bowl and place over ice water bath. Chill until mixture is thick enough to fall from a spoon in ribbons

Step 4: White Chocolate Mousse

Whip remaining 1 3/4 cups heavy cream to soft peaks.

Fold into chocolate mixture. If not using immediately, refrigerate in an airtight container.

Step 5: Dark Chocolate Mousse

INGREDIENTS

8 largs eggs, separated
8oz dark (or semisweet) chocolate, chopped
1 tbsp instant coffee
1/4 cup boiling water
2/3 cup granulated sugar
1 tsp vanilla extract
1 tsp salt

In a small bowl, dissolve the coffee in the hot water, then add to the chocolate.

Melt chocolate in a stainless steel bowl over simmering water.

Step 6: Dark Chocolate Mousse

In a medium mixing bowl, use an electric mixer to beat the egg yolks on high speed for 5 minutes, until they’re lightened and thickened.

Slowly stream in the sugar while beating, then continue to beat on high speed for 5 more minutes. The yolks will be very thick and a little sticky.

Add the vanilla and chocolate and beat them in slowly, scraping down the bowl.

Set aside and wash and dry the mixer’s beaters well.

Step 7: Dark Chocolate Mousse

Put the egg whites in another mixing bowl and add the salt. With those clean, dry beaters, beat the whites until they hold soft peaks, but not until they are stiff or dry.

Step 8: Dark Chocolate Mousse

In two or three small additions, fold about half of the egg whites into the egg yolk-chocolate mixture – no need to be very thorough. Then fold the chocolate into the remaining whites. Fold only until no egg whites show, using big but gentle movements so as not to deflate all those egg whites you just inflated with air.

Refrigerate until ready to use.

Step 9: Ganache

INGREDIENTS

3oz dark chocolate, chopped
1/4 cup heavy whipping cream

place both the heavy cream and the chocolate in the top of a double boiler, or a heatproof bowl.

Heat over low heat until chocolate is melted.

Stir until smooth.

I placed it in a piping bag to be able to draw on the pie with it. It cools quickly however, and then becomes lumpy and does not write quickly. Make this as close to assembly as possible.

Step 10: Assembly

I made a little cardboard/tinfoil barrier in which to contain the white chocolate mousse.

Add the dark chocolate mousse to the rest of the area (I neglected to take a picture of this)

Step 11: Pi Pie

Remove the cardboard barrier between the white/dark mousses.

Place the rest of the mousse's into piping bags and use a spoon or offset spatula to smooth out the top of the pie.

Use the piping bags, and whatever tips you prefer, to decorate the top of the cake as such.

My white chocolate corners actually go all the way through the pie. I just used a spoon to push the chocolate away from the corners and used the white chocolate mousse piping bag to fill the corner in.

Use the ganage to create the text, or just use more of the mousse (as in the case of the white text).

Voila :) Mathmatically accurate Pi Pie!