If the diameter of the circle (r) is 1, The area of the circle is 1x1xπ = π. To make a square of which area equals that of the circle, one edge must be the square root of pi (√π).
In this case, the diameter of the strawberry pie is 4.5 inches, so an edge of the rhubarb pie should be about 8 inches.
Crust: All butter pie crust with almonds
Make the double crust recipe. Use 1/2 for the bottom crust, and the other half for the square crust.
Make a single crust in a 9-inch pie dish and blind bake. Let it cool completely.
1) Yogurt mousse:
1/2 cup plain yogurt
1/4 cup heavy cream
1/2 teaspoon ground black cardamon
2 teaspoons unflavored gelatin, soaked in 1 tablespoon of water
1/8 teaspoon salt
3 large egg whites
6 tablespoons sugar
1/4 teaspoon cream of tartar
Combine yogurt, heavy cream and cardamon.
In a double boiler on low heat, whip egg whites with salt, cream of tartar, with gradual addition of sugar, until the temperature of the egg whites reaches 160F and the meringue forms soft peaks.
Microwave soaked gelatin for 30 seconds or until melted, watching carefully not to boil over. Quickly add to the yogurt mixture and immediately fold in egg whites.
Pour the mousse into a blind-baked crust. Chill until set.
2) Strawberry-balsamic topping:
1lb strawberries (thawed if frozen)
1/2 tablespoon balsamic vinegar
1/3 cup sugar
1 teaspoon unflavored gelatin, soaked in 2 tablespoons of water
strawberries, sugar, balsamic vinegar, gelatin
Combine strawberries and sugar in a pot, and cook until it becomes slightly syrupy consistency. add balsamic vinegar.
Add gelatin and cook until melted. Let it cool at room temperature.
When the yogurt mousse is set, pour the strawberry topping onto it and chill.
3) Rhubarb filling:
12 oz rhubarb
1/3 cup sugar
1 tablespoon cornstarch
The square pie:
Roll out a pie dough to an 8-inch square. Top the crust with the rhubarb filling. Bake at 375ºF until the edges are golden and rhubarb is soft, about 20-30 min. Cool completely before putting it on top of the strawberry pie.
Roll out any leftover dough, cut out arrows, letters and symbols with a paring knife. Bake them until golden brown. Mix a teaspoon of cocoa powder with a teaspoon of powdered sugar, and drops of water enough to make a paste to paint some of the cut-out crust.