Lay some paper towels on top of a sieve and dollop the yogurt on top. Put the sieve on a bowl, wrap it with cling film and leave to drain in the fridge overnight.
Line the baking tray with baking paper. Separate the egg yolks and egg whites. Sift the cake flour. Preheat the oven to 200°C.
Add the egg whites to a bowl with the sugar and whisk into a meringue that forms stiff peaks.
Add the lemon zest and mix well. Add the egg yolks one by one and mix in well.
Add the cake flour and fold in with a rubber spatula. When the powder is incorporated, pour in the cream and continue to mix.
Pour the batter into the baking tray and even out the top. Bake for 8 - 10 minutes at 180°C. Once the cake has turned a golden colour, check to see if it's done by inserting a skewer.
Take the sponge and baking paper out of the baking tray together and cool on a wire rack. Place the baking tray over the sponge and let it cool (you can wrap it with cling film as well).
Add the cream and sugar to a bowl and whip it until stiff peaks form. Add the drained yogurt and lemon juice and mix well.
Once the sponge has completely cooled, lightly cut some lines into the back of the cake. Cut off a piece of sponge diagonally at the far end as in the photo.
Spread the cream onto the sponge, piling it up more on the side closest to you and roll it away from you. Wrap tightly with baking paper and let it rest in the fridge for 1 hour.
Cut off both the ends to neaten it up and your done.
If you try making double the amount of cream, you can decorate the outside of the roll cake too, which will look nice.
Story Behind this Recipe
I just wanted to come up with a recipe that used drained yogurt.
If you're making cream to decorate the outside of the swiss roll, whip it up until it is stiffer than the cream that you spread inside. I recommend low-fat cream. I drained the yogurt down to 70 g from 150 g.