* butter for greasing tin
* 3 large eggs
* 100g caster sugar
* 1 tsp vanilla extract
* 115g plain flour
* 150g seedless reduced sugar
* raspberry jam
* caster sugar for sprinkling
1) Grease the base and sides of a 33 x 23cm Swiss Roll tin and line it with baking parchment. Preheat the oven to 200C/Fan 180/Gas 6. Put the eggs, sugar and vanilla in a heatproof bowl and place the bowl over a pan of gently simmering water. Whisk with an electric whisk until the mixture is pale, creamy and thick enough to leave a trail when you lift the whisk.
2) Carefully remove the bowl from the heat and whisk for a further 5 minutes. Sift over half the flour and, using a large metal spoon, lightly fold the flour into the egg mixture. Sift over the remaining flour and fold it in. Be gentle to keep as much air in as possible.
3) Pour the mixture into the prepared tin and gently spread it with a spatula, so the base of the tin is evenly covered. Bake for 10 mins until well risen, pale golden and firm to touch.
4) While the sponge is cooking, place a damp tea towel on the work surface and cover with s sheet of baking parchment. Sprinkle with a tablespoon of sugar. Quickly turn the cake out onto the sugared paper and carefully remove the baking parchement from the sponge.
5) With the long side of the cake facing you, cut off thin strips of the crusty edges from the sides. Score the sponge lightly with a sharp knife from top to bottom about 2.5cm in from the left hand side to help make a tight turn when you start to roll the sponge, but do not go all the way through.
6) Spread the sponge all over with the jam. Roll the Swiss roll from the scored end, starting with the tight turn tom make a round shape. Leave to cool on a wire rack and the cut into slices.