for the dough
Separate the eggs, put the egg whites in a large bowl and whisk together with the pinch of salt until foamy. Add sugar and beat egg whites until smooth.
Add the egg yolks one at a time and continue beating the mixture briefly. Add oil and incorporate into the mixture. Sift the flours, baking powder and vanilla and incorporate into the mixture.
Spread the dough on the buttered cookie sheet lined with parchment paper and smooth it out.
Bake the dough in a preheated oven at 190°C for 10 minutes. Then turn off the oven, open the door slightly and let the dough rest for another two and a half minutes before removing it from the oven.
Remove the dough from the cookie sheet, cover with a damp dishtowel and let rest for 20 minutes.
Turn the dough over so that it lies on top of the damp towel and remove the parchment paper. Then place the parchment paper back on the dough, cover the edges with the towel and roll the dough into a roll. Let rest and cool completely.
for the filling
Mix corn starch and sugar in a saucepan and gradually add milk until the corn starch has dissolved. Add lemon zest and heat the saucepan over medium heat. Cook, stirring constantly, until the pudding thickens.
Remove from heat, remove the lemon zest and cover with cling film. Set aside until completely cool.
Meanwhile, whip cream, vanilla and cream stiffener and refrigerate.
Once the milk pudding is completely cooled, beat again for 5-10 minutes until it is creamy again.
Gradually add the pudding to the cream and continue beating. Place in the refrigerator for 30 minutes.
Roll out the dough and remove the parchment paper as well as the towel. Spread all the filling on the sponge cake base and smooth it out.
Roll the dough back up to form a roll and let the roulade rest in the refrigerator for at least 2 hours.
Decorate with powdered sugar and serve.
The roulade can be enjoyed as it is or together with fresh berries or coulis.