Chocolate Roulade

Preheat the oven to 200°C (approximately 400°F).

For the cake: Separate the eggs. Beat the yolks with half the sugar, the salt, and the lemon zest until fluffy. Whip the egg whites until stiff. Gradually sprinkle in half the sugar and continue to whisk until stiff. Whisk the whites into the yolks. Mix the flour with the cornstarch and fold into the egg mixture. Line a sheet tray with parchment paper. Spread the batter in the pan and smooth. Bake in the oven for 10-12 minutes. Turn the cake out onto a tea towel, sprinkled with sugar. Peel off the parchment paper and roll up the cake with the towel lengthwise into a roulade. Let cool.

For the filling: Whip the cream with the sugar and vanilla sugar until stiff. Fold in the cocoa powder. Chill the filling.

For the chocolate cream: Cook the milk, sugar, and custard powder according to the instructions on the package. Cook into a pudding and let cool to room temperature.

Chop the dark chocolate and melt in a bowl over a pot of simmering water. Remove from heat and let cool. Make sure that all the ingredients for the chocolate cream are at the same temperature. Beat the butter with the powdered sugar until fluffy. Fold int the melted chocolate once cooled. Remove the skin from the top of the pudding and stir the pudding into the chocolate mixture.

Carefully unroll the cake. Remove the towel. Brush with the cream and spread with the 2/3 of the chocolate cream. Reroll into a roulade.

Cover the roulade with the remaining chocolate cream and draw grooves in the side with a toothpick or a fork, like a tree.