Preheat the ovent at oven at 350°F (convection).
Begin by making the dough. Separate the eggs and beat the egg whites until stiff. Gradually add the salt and sugar while beating, then whisk in the egg yolks.
Mix the flour and baking powder, sift it into the egg mixture, and then fold it in.
Spread the dough on a baking sheet lined with parchment paper and smooth it out.
Bake the sponge cake for 10-12 minutes.
Turn the cake out onto a damp kitchen towel sprinkled with sugar.
Carefully peel off the parchment paper and gently roll up the cake with the towel. Let it cool.
Sprinkle 5 teaspoons of pwdered gelatin over cold water and let it bloom for a few minutes. Meanwhile, in a bowl, mix the yogurt, yogurt, ⅓ cup sugar, lemon zest, and lemon juice.
Now, stir a little bit of the cream into the gelatin. Then add the gelatin-cream mix to the rest of the cream. Chill the filling for about 5 minutes until it starts to set.
Beat the heavy cream until stiff and then fold it into the larger cream mixture.
Unroll the cake and evenly spread the cream across it. Now, roll the cake up again and let it chill for at least 3 hours.
Garnish with powdered sugar and fresh mint before serving.
