Directions

1. To make the sponge, preheat oven to 160ºC. Line a baking tray with a 30cm x 42cm sheet of baking paper. In a large mixing bowl, beat the eggs, sugar and vanilla with an electric beater on medium speed until the mixture becomes very thick, fluffy, and yellow in colour. Fold in the butter and water until combined. Sift the cocoa powder, flour and baking powder over the wet ingredients and fold through gently until the mixture is smooth and streak-free. Pour the mixture evenly onto the baking paper and smooth the surface. Bake for 10 – 12 minutes or until the sponge springs back when touched. Remove the sponge from the oven, peel it from the baking paper and turn the top side down onto a clean sheet of baking paper. Trim edges to straighten. Roll up the sponge from the short side, using the baking paper to help it roll. Leave the sponge rolled in the baking paper and wrapped in a tea towel until it cools completely.
2. Once cold, unroll the sponge. Spread cherry jam thinly across the sponge. Then spread the cream mixture across the sponge leaving a 3cm gap along one of the short sides (the outside of the roll). Re-roll the sponge tightly into a log shape. Drizzle the chocolate butter icing across the top of the log.
3. To make the cream filling, in a mixing bowl whisk the mascarpone, icing sugar and vanilla with an electric whisk or beater on medium–high speed until well combined. Very slowly drizzle in the cream and continue to whisk the mixture until all the cream is incorporated and stiff peaks have formed.
4. To make the chocolate buttercream, place the chocolate, butter and cream in a heatproof bowl set over a pot of lightly simmering water, ensuring that the water doesn’t touch the bottom of the bowl. Whisk the mixture until all the chocolate is melted and fully combined with the cream and butter.