Preheat the oven to 350 degrees.
Separate the yolks and whites into 2 separate bowls. Add ½ of the sugar to each bowl. Beat the yolks and the whites until stiff peaks form. Fold the whites into the yolks. Gradually add the flour, mixing with a wooden spatula. Mix in the butter.
Grease a 10-inch cake pan and pour in the mixture. Bake until spongy and golden, about 20 minutes. Remove from the oven and let cool completely. Level the sponge cake off at the top using a slicing knife. Cut the cake into 2 layers.
Spread the flavored pastry cream over 1 layer. Top with the second cake layer. Reserve a small amount of the pastry cream to spread on the sides to adhere to the almonds. Spread a thin layer of chocolate icing on top of the cake. Follow immediately with spiral lines starting from the center of the cake, using the white icing.
Score the white lines with the point of a paring knife, starting at the center and pulling outward to the edge. Spread a thin coating of the reserved pastry cream over the sides of the cake and press on the toasted almonds.