Pre-heat the oven to 180c and line a Swiss roll tin (around 31cm x 21cm) with non-stick baking paper
Using an electric hand whist, whisk the eggs, sweetener, 50g caster sugar and vanilla extract together in a bowl for 4 minutes until light and fluffy. Sift over flour and cocoa power and gently fold in.
Spoon the mixture into the prepared tin and spread it out evenly, making sure it goes into the corners of the tin. Bake for 10 minutes until firm and springy to the touch. Remove from the oven.
Place a clean sheet of non-stick baking paper on to your work surface and sprinkle with the remaining caster sugar. Turn the sponge out on to the sugar dusted paper and peel off and discard the old baking paper. Starting with one long edge, roll up the sponge together with the paper and leave it to go cold.
To make the filling, beat the quark and raspberry yoghurt together until smooth. Carefully unroll the sponge and spread the yoghurt mixture over it. Roughly crush half the raspberries with a fork and spread over the yoghurt. Roll up the sponge once more, this time without the paper.
Carefully lift the log on to a serving board and decorate with the remaining raspberries. Sprinkle over the remaining icing sugar and serve straight away for the best results.
From p. 108 of Slimming World's 'Festive Feasts' book.
The Slimming Foodie has no official affiliation with, or endorsement from Slimming World. Slimming World’s website can be found at https://www.slimmingworld.co.uk. The syn values shown on my recipes are my personal estimation and have not been verified by Slimming World.