To make the pastry wafers: Preheat the oven to 350° F. Lightly film a baking pan with vegetable spray. Draw 16 (2-inch) circles (leaving 1 inch between circles) onto the baking pan, using either a round biscuit cutter or a glass.
In a large mixing bowl sift together the confectioners' sugar and flour. Whisk in the egg whites, working them into the flour and sugar until smooth and well incorporated. Whisk in the melted butter and vanilla extract. Spoon the mixture onto the drawn circles, using a circular motion to fill the space completely. Bake for 8 to 10 minutes or until golden brown.
Remove the cookies from the oven and cool on a rack. Use a cake spatula to carefully lift the baked cookies off the pan.
To make the Key lime custard: Preheat the oven to 325° F. Lightly grease a small baking dish with butter.
In a large mixing bowl combine the zest from the Key limes, sweetened condensed milk, and Key lime juice and whisk together. Add the 3 egg yolks and whisk together until well blended (the mixture will turn bright yellow). Pour the mixture into the prepared baking pan, and place in the upper third of the oven. Bake for 20 minutes or until set. The center of the custard will feel firm to the touch. Remove to a rack and let cool overnight.
To make the whipped cream: Place the heavy cream in the well-chilled bowl of an electric mixer fitted with a well-chilled balloon whip. Whip on low speed until the cream is frothy. In a steady stream add the sugar and whip, gradually increasing the mixer's speed until the cream begins to form peaks. Add the vanilla extract and whip until soft peaks form. Or you may make by hand in a large mixing bowl, with a large balloon whisk.
To make the pastry cream: In the clean bowl of an electric mixer fitted with a whisk, beat the egg yolks with sugar on high speed until the mixture is thick and pale yellow.
Sift the flour and cornstarch together and whisk into the egg yolk mixture.
In a nonreactive saucepan scald the milk with the vanilla bean. Pour about one-fourth of the hot milk into the egg yolk mixture, whisking constantly. Return this mixture to the saucepan, whisking constantly until the mixture thickens, reaching a pudding-like consistency. Remove the pan from the heat and blend in the butter. Strain into a bowl and cover with film wrap, pressing down on the surface of the cream so that a skin will not form. Cool. Refrigerate until needed.
To make the Key lime sauce: In a medium mixing bowl whisk together the Key lime juice, pastry cream and green food coloring.
To assemble: In the center of a dessert plate place one pastry wafer. On one side of the wafer place a 2-ounce scoop of Key lime custard. Place a second wafer on top of the custard, and top with another 2-ounce scoop of custard. Repeat for one more layer, finishing with a fourth wafer. Dust the top with confectioners' sugar, and garnish the plate with Key lime sauce, whipped cream, raspberries, mint and slices of lime.Makes 4 Source: