This log has nothing to do with the winter firewood, this cake (fatörzs in Hungarian) is a premium version of swiss roll: a simple sponge cake roll filled and covered with an orange flavoured chocolate filling. Sponge cake is very versatile, a base of many Hungarian tortes and desserts.
Piskóta is a light and airy foam cake consisting of egg, flour and sugar. As it has no added fat, it’s not so easy to bake good sponge cake. The traditional piskóta doesn’t contain baking powder or soda because leavening comes entirely from the air trapped in the beaten egg whites. Inspite of that I add baking powder to the batter as I had bad experiences when I wanted to bake sponge cake in the traditional way.
As regards the baking, it’s very important to preheat the oven and bake the sponge cake as soon as it is ready or the egg whites will deflate; opening the oven during the baking process can also cause deflation. It’s your choice if you grease and flour the baking pan or line it with parchment paper; latter is preferable because it makes easier to turn out the dough from the pan.
For the sponge cake:
- 6 eggs, separated
- 6 tbsp sugar
- 6tbsp flour
- pinch of salt
- 3/4 tbsp baking powder
For the filling:
- 3 eggs
- 2 tbsp cocoa powder
- 130 g (~2/3 cup) sugar
- zest of an orange
- 200 g (~7 oz) butter
Size of the baking pan: 33×33 cm
Preheat the oven to 180°C. Line a baking pan with parchment paper. Add a pinch of salt to the egg whites and beat until stiff. Beat the egg yolks and sugar until thick and pale yellow colored. Stir the flour and baking powder into the yolk mix. Gently fold the beaten egg whites into the yolk mixture. Pour the batter in the prepared baking pan and smooth out the top. Bake for about 20-25 minutes until golden brown. Carefully invert the cake on a clean tea towel and peel away the paper. Using the towel, roll it up from the short side and let it cool.
In the meantime make the filling. Whisk eggs, sugar, orange zest and cocoa powder together, and over a pot of simmering water cook, while whisking continuously, until thick – it takes about 10 minutes. Set aside and let it cool. Whip the butter. Once the cocoa cream filling is cool, add soft whipped butter and whisk until well combined.
Unroll the cake and spread with 2/3 of the filling. Re-roll the cake and place, seam-side down, on a plate. Spread the remaining filling over top and sides evenly, then with a fork decorate the roll by drawing wavy lines.