In a bowl, whisk together the flour, cocoa powder, baking powder, and salt until well combined. Set it aside for later use.

In another bowl, use an electric mixer to beat the eggs, vanilla sugar (if using), and granulated sugar for about 5-6 minutes, until pale, thick, and tripled in volume.

Gently fold the vegetable oil and milk into the egg mixture until well blended.

Sift half of the flour mixture over the egg mixture. Carefully fold it in from the bottom to the top to maintain airiness. Repeat with the remaining flour mixture.

Pour the batter into a parchment-lined baking pan and bake at 170°C (340°F) for about 13-15 minutes.

Once done, cool for 2-3 minutes, then turn the cake onto a cooling rack and remove the parchment. Let it cool completely.

Using a round glass or cookie cutter, cut circles from the cooled sponge cake.

In a small bowl, mix the gelatin with water and let it bloom for 7-10 minutes.

In a large bowl, whip the cream with powdered sugar until stiff peaks form. Fold in the desiccated coconut.

Microwave the bloomed gelatin briefly to melt it, then mix it with a small amount of the whipped cream to temper. Gently fold this mixture into the remaining whipped cream.

Fill hemisphere molds halfway with the coconut mousse. Add a dollop of chocolate-hazelnut spread in the center and cover it with more mousse. Press a sponge round on top, flattening it slightly.

Freeze the molds for 2-3 hours until completely frozen.

When ready to serve, remove from the molds, let thaw for 15-30 minutes, and roll in extra coconut flakes before enjoying.