Heat oven to 180C/160C fan/gas 4. Grease and line a 16 x 28cm Swiss roll tin with baking parchment.
Beat the eggs and sugar together for 5 mins with an electric whisk until thick and pale. Gently fold in the flour in two batches using a large metal spoon. Pour the mixture into the tin and gently ease into the corners. Bake for 10-12 mins until golden and firm. Be careful not to overbake, or the sponge will break when rolled.
While the sponge is baking, sprinkle 2 tbsp sugar over a square of baking parchment. Warm the jam in the microwave for 20 secs.
Turn the baked sponge onto the sugared paper. Peel off the lining paper and spread the sponge with the warm jam. Roll up from the short edge using the paper to help you then cool on a wire rack.