<p>Set oven to 180 C, 350 F or Gas Mark 4.</p><p>Line your Swiss roll tin with baking parchment or grease-proof paper.</p><p>Combine the eggs and sugar and whisk until thick and foamy. This can take up to 5 minutes. This is one recipe where you really need a food processor with a whisk attachment or an electric whisk rather than attempting to do it with a hand whisk.</p><p>Fold the flour and baking powder into the foamy egg and sugar mixture.</p><p>Pour the combined mixture into your enameled gn container.</p><p> Put the tin in the oven and bake the sponge for 15 minutes until firm and golden.</p><p>Turn the cooked sponge onto another sheet of baking parchment or grease-proof paper on which you have sprinkled around a tablespoon of caster sugar.</p><p>While the sponge is still warm, roll it up so it looks like a Swiss roll with the paper inside. You need to roll it up while it is warm – you can’t do this when it has cooled off as the cake will crack! Allow to cool completely.</p><p>Know, unroll the sponge and remove the paper. Spread your jam over the sponge and top it with the whipped double cream.</p><p>Roll the filled cake up into a Swiss roll shape again.</p><p>Dust with sieved icing sugar.</p>