- 5 medium eggs
- 115g caster sugar
- 110g plain flour
- 1 tsp baking powder
- 1 tsp vanilla extract
- 2 tsp boiling water
- 1 tsp Dr. Oetker Gel Food Colour in Bright Red
- 300ml double cream
- 1 tbsp icing sugar, plus extra to decorate
- 200g pack raspberries, crushed with a fork
- 2 tbsp Chambord liqueur
- Berries, to decorate
Preheat the oven to 200C/180C Fan/Gas 6. Oil a 37cm x 25cm Swiss roll tin and line with baking paper. Separate 1 egg and set aside 1/2 tsp of the white. Using the rest of the egg plus the other 4 eggs, whisk with the sugar for 5 minutes until pale and thick. Sift the flour and baking powder together - repeat 3 times. Add to the egg mixture with the vanilla and water. Fold together.
Spoon three-quarters of the cake mixture into the tin and spread evenly. Stir the red gel into the remaining mixture then put in a piping bag with a plain, medium nozzle. Pipe diagonal lines across the plain mixture.
Cook for 18 minutes until golden and the sponge springs back when pressed lightly.
Turn out the sponge onto clean baking paper. Peel off and discard the paper liner it was baked on. Roll up the sponge together with the new baking paper. Cool on a rack, then unroll. Discard the paper.
Whip together the cream and icing sugar until soft peaks form. Fold in the raspberries and Chambord. Spread over the unrolled sponge. Re-roll and put on a serving plate.
Brush the berries with the reserved egg white, sprinkle with icing sugar to frost, then arrange on the cake.