Preheat oven to 180°C/350°F. Add part of the eggs and the sugar to a standing mixer. Beat until the color of the mixture is very pale and it has grown in volume. Add lemon zest. Sift flour, cornstarch, cocoa powder, and a pinch of salt into the mixer bowl. Beat until a smooth dough forms.

standing mixer or hand mixer with beaters, oven, fine grater

5 eggs / 150 g sugar / 0.5 lemon (zest) / 100 g all-purpose flour / 50 g cornstarch / 50 g cocoa powder / 1 pinch salt

Add vegetable oil to the dough and incorporate.

measuring cup, spatula

50 ml vegetable oil

Transfer dough to a lined baking sheet and even out surface. Bake in preheated oven at 180°C/350°F for approx. 10 – 15 min. Remove from oven and place on a wet kitchen towel. Carefully remove parchment paper and use the towel to gently roll your cake. This way you prevent the surface from cracking and ensure that you will be able to form a nice cake roll later.

baking sheet, oven, kitchen towel (wet), parchment paper

Gently melt chocolate over a water bath over medium heat. Once it has melted, set aside.

large bowl, small saucepan

280 g chocolate (bittersweet) / 150 g chocolate (milk)

Separate part of the eggs. Add yolk as well as remaining eggs to a large bowl. Place bowl on the water bath and whisk eggs until they are thickened.

large bowl, whisk

1 egg yolk / 4 eggs

Beat cream until stiff. Add molten chocolate, orange zest, and instant espresso powder to the eggs and incorporate. Set aside to cool for approx. 10 min. When the mixture has cooled, gently fold whipped cream into chocolate mixture. Transfer to refrigerator and chill for approx. 1 h.

standing mixer or hand mixer with beaters, fine grater, spatula

850 ml whipping cream / 1 orange / 1 tsp instant espresso powder

Distribute two thirds of the cream over the cake and roll it up. Place on a long serving plate and decorate with remaining cream. It is traditional to pull the tines of a fork over the cream to make it look like tree bark. Bon appétit!