For the jaconde: Preheat the oven to 375 degrees F. Line a baking sheet with parchment paper and coat lightly with butter.
Combine the 13 ounces egg whites and the granulated sugar and whip into a meringue with stiff peaks, using an electric mixer.
Sift the almond flour, all-purpose flour and confectioners' sugar into a bowl. Add the heavy cream and the remaining 4 ounces egg whites to make a paste. Fold one-third of the meringue into the paste; once incorporated, fold in the remaining meringue. Pour into the prepared baking sheet and sprinkle the top with desiccated coconut.
Bake for 15 minutes, then flip the cake out of the baking sheet and let cool. Soak the jaconde with fruit puree, making sure the sponge is wet but not soaked.
For the ganache: Heat the heavy cream in a saucepan until boiling. Remove from the heat and pour into a bowl with the white chocolate. Let sit for 5 minutes, then stir until smooth. Let sit until cool, about 30 minutes.
Whip the ganache with an electric mixer until thick and creamy.
Spread the ganache on the cake, and slice. The cake can also be chilled.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.