Preheat the oven to 160°C fan (180°C non-fan). Grease 2 rimmed baking trays/Swiss roll tins (around 23cm by 32cm) with a bit of butter and line each with a sling of baking paper. Set aside.
Combine the eggs and sugar in a large bowl and whisk using electric beaters until very thick, pale and at least tripled in volume - around 5 minutes.
4 large eggs, 100 g caster sugar, golden caster sugar or granulated sugar
Add the self-raising flour to the bowl then gently fold together with a spatula or metal spoon until no floury streaks remain. Divide the batter between the two prepared baking trays and spread out to cover the entire tray.
100 g white self-raising flour
Bake the cakes for 10-12 minutes, until golden-brown on top and cooked through.
As the cakes bake, cut two large pieces of baking paper and sprinkle them with a bit of sugar (caster sugar, preferably).
Once the cakes have baked, remove from the trays and flip onto the pieces of sugar-sprinkled baking paper. Use a pair of scissors to trim the very edges of the cakes.
Starting at the short edge of a cake, roll up WITH the baking paper (this stops the cake sticking to itself) into a tight log. Repeat with the second cake then set them aside, seam side down, to cool.
If you're making this ahead of time: wrap the rolled up cakes with their baking paper in clingfilm, tightly. Leave at room temperature for up to 1 day.