Pre-heat your oven to 200°c (180°c for fan assisted ovens or Gas Mark 3). Generously grease a 30cm x 22cm Swiss Roll Tray and line the bottom with greaseproof paper. Set aside. In a large bowl, gently whisk the eggs until the whites and yolks are combined, before adding the caster sugar. Whisk the eggs and sugar until you have a pale and thick mixture.This is much easier when using an electric hand whisk but can also be done by hand.
Sift the flour into the mixture and gently fold together to create a light batter, being careful not to over mix. Pour the batter into your prepared tin and evenly spread to the sides and corners.
Bake in your pre-heated oven for 7-8 minutes until a light golden colour and dry in appearance.Whilst the sponge bakes, place an additional piece of greaseproof paper on a flat surface and dust with a little caster sugar. Warm the jam, either in the microwave or over a bain marie - this isn't essential but it will make your jam easier to spread.
Take the sponge from the oven, run a knife around the edges of the cake to loosen it from the tray and gently tip it from it's tray onto the sugared greaseproof paper. Trim the edges of the sponge and remove the baked-on greaseproof paper.
Spread the jam on the sponge, right to sides but leaving a little gap at the shorter ends. Gently fold one about 1cm of one of the shorter ends over (gently press with a knife to mark first, if required); this is the start of your rolling.
Using the greaseproof paper, continue to roll the sponge over itself, using gentle pressure to make sure there is no big gaps. Finish by ensuring the end is on the underside of the Swiss Roll; the weight of the rest will stop it from unravelling.
Dust with a little more sugar if desired and allow to cool completely before cutting.