Preheat the oven to 200 °C / 400 °F. Place the rack in the middle of the oven. Grease a 20 cm (8-inch) round non-stick springform cake pan. Don't forget to grease the sides too.
make the cake batter
Separate the yolks from the whites. Add egg yolks to a large bowl and egg whites to a small bowl. Add the sugar and vanilla to the yolks. Using an electric mixer, mix the egg yolk mixture for about 3 - 4 minutes, or until fluffy and pale. Clean the whisks and whip the egg whites until stiff peaks form. Stir half of the egg white mixture into the egg yolk mixture using a spatula. Add in the sifted flour and stir to get a smooth mixture. Fold the rest of the egg whites into the egg yolk mixture. Do it gently and try keeping the volume.
bake the cake batter
Pour the sweet omelette batter into the prepared cake pan. Spread evenly. The easiest way to do this is by shaking the pan around to evenly distribute the batter. Place in the preheated oven. Bake for 8 minutes at 200 °C / 400 °F. Remove from the oven and remove from the pan while still hot. Transfer to a wire rack. Place a small rolling pin or a 500ml bottle in the middle and fold over to get a taco-shaped form. Set aside for 3 - 5 minutes to cool slightly.
decorate and serve
Add whipping cream and icing sugar to a bowl. Whip on medium speed until stiff peaks form, keep an eye on it to not overwhip. Carefully and gently remove the rolling pin from the omelette. Optionally brush with liqueur, then spread the cranberry jam over the whole cake. Support the cake with your hands to prevent it from cracking. Arrange fresh berries on top. Save about a tablespoon of berries for the decoration. Decorate with whipping cream using a pastry bag or a spoon. Arrange the rest of the berries over the whipped cream. Optionally sprinkle with some mint leaves and dust with icing sugar, then serve.