1Preheat oven to moderately hot, 190 C. Line a 20 x 30 cm Swiss roll pan with baking paper.
2In a medium bowl, using an electric mixer, beat eggs and sugar together 4 to 5 mins until thick and pale. Sift flour and cocoa together over egg mixture. Gently fold in.
3Spoon mixture into pan, smooth surface. Bake 8 to 10 mins until cake springs back when touched.
4Turn out onto a clean tea towel and carefully peel off baking paper. Trim edges. Gently roll up cake in a tea towel. Set aside to cool completely.
5GANACHE: Meanwhile, in a small saucepan, heat cream on medium until almost boiling. Remove from heat. Add chocolate, stirring until smooth. Chill 10 mins until spreadable.
6Unroll cooled sponge. Brush with liqueur. Spread with cream. Roll up and place seam-side down on a piece of baking paper. Trim one end diagonally.
7Secure cut end to side of log with a little ganache to form branch. Spread remaining ganache over cake to cover. Drag fork across the surface to create a wavy pattern to resemble bark. Sprinkle with hazelnuts.
TIP: Roll cake while still hot to help prevent cracking.
Photo: Rodney Macuja/Bauer