1. Preheat the oven to 190°C,180°C fan, Gas mark 5. Grease and line a 30cm x 22cm Swiss roll tin with greaseproof paper, lightly grease the greaseproof paper as well.
2. Whisk the eggs and sugar together until the mixture forms a trail for 1-2 seconds when the whisk is lifted out of the bowl. Whisk in the vanilla essence.
3. Gently fold in the plain flour with a metal spoon until no flour remains. Gently fold in the melted Stork until blended. Pour into the Swiss roll tin and tilt to run into the corners of the tin.
4.Bake for 10-12 minutes until light and springy to the touch. Whilst baking cut a piece of baking paper slightly larger than the Swiss roll tin and place on a worksurface and sprinkle lightly with caster sugar.
5.Turn out the Swiss roll onto the sugared paper and carefully peel off the lining paper, then trim the edges of the Swiss roll. Carefully roll up the Swiss roll in the greaseproof paper and leave to cool on a cooling rack.
6. To make the ganache: put the Elmlea, Stork and vanilla into a saucepan and heat until just simmering, remove from the heat, add 150g of the chocolate, stir until melted, then pour into a bowl and leave to cool, then refrigerate.
7. When the filling is cold, whisk until light and fluffy. Carefully unroll the Swiss roll and evenly spread half the ganache over the sponge.
8.Lightly tear the raspberries and sprinkle over the filling. Roll up the Swiss roll and place on a serving plate. Spread remaining ganache over the log with a palette knife to give the impression of bark.
9. Optional, for the Christmas trees melt 50g white chocolate very gently, but do not overheat, otherwise the chocolate won’t set. Pour into a piping bag fitted with a very small nozzle. Pipe abstract tree designs onto silicone paper and leave to set. When set use a thin palette knife to carefully remove from the silicone and stick to the sides of the Swiss roll. Serve with extra raspberries and mint leaves and sprinkle with icing sugar.