Preheat oven to 250 degrees.
To make meringue: Beat 3 egg whites until almost stiff. Sprinkle in 1/3 cup granulated sugar and 1/8 teaspoon vanilla extract, beating until stiff, glossy peaks form. (Warming the bowl and beater in warm water and drying carefully before using helps ensure high volume.) Add confectioners' sugar and blend quickly and thoroughly by hand using a rubber spatula. Transfer meringue onto a baking sheet lined with parchment paper. Spread over parchment to a depth of about 1 to 1 ½ inches. Place in oven for about 1 hour or until meringue is dry. Break meringue into 1 inch chunks and set aside.
Increase temperature of oven to 400 degrees. Sift flour, baking powder and salt together; set aside. In a large bowl, mix eggs and 1 cup granulated sugar with electric mixer on high speed. Add 1/4 cup water an continue beating until mixture is fluffy and pale yellow. Stir in flour mixture and blend by hand thoroughly and quickly. (If this step is not performed quickly, the eggs will lose their volume.)
Pour mixture into a lightly greased 12 inch by 9 inch cake pan and tap firmly once or twice on the counter to remove any air bubbles. Immediately place pan in oven. Bake for 10 to 13 minutes, or until cake tester comes out clean when inserted in the middle. (It is better to dry out the cake a little rather than have it under cooked at this stage.) Remove cake and let cool. Meanwhile, whisk together the condensed milk, evaporated milk, ¾ cup heavy cream and liqueur. Using a toothpick, poke holes in cake and pour the milk mixture over the top. Refrigerate. In a well chilled bowl, using chilled beaters, beat the heavy whipping cream and remaining extract until stiff peaks form.
To assemble: Cut cake into pieces with a 3 inch diameter cookie cutter. Put a scoop of whipped cream on top; garnish with chunks of meringue. Surround with slices of banana, a couple of prunes and a smidgen of prune juice for additional garnish.