Preheat the oven to 180ºC/350ºF/Gas mark 4

Grease and line the bottom and sides of a Swiss roll tin or large baking tray with parchment paper

Sift the flour(s) and salt into a mixing bowl from a height to incorporate air

In a large mixing bowl, whisk together the caster sugar, vanilla extract and the egg yolks until the mixture is pale, airy and shiny

Whisk in the melted butter

Fold the flour carefully into this mixture, trying not to beat too much air out of the mixture. Set aside

In another mixing bowl, whisk the egg whites to soft peaks (use a stand mixer/electric whisk for ease and speed)

Gently fold the whites into the mixture in three stages

Pour the mixture into the lined tin and tilt from side to side to cover evenly

Gently bang the tin on to the workspace a couple of times to get rid of any air bubbles

Bake for 10-12 minutes until golden brown and springs back when pressed with a finger

Spread a clean, damp tea towel on a work surface

Cut a piece of greaseproof a little larger than the tin, lay it on the tea towel and sprinkle over the extra caster sugar

Loosen the sponge around the edges and then invert on to the paper with one of the short sides facing you

Trim the 4 edges using a bread knife to neaten

Gently score a straight line from end to end around 1cm from the edge closest to you

Whilst still warm, roll the sponge up as tightly as possible, rolling the paper in with it using the damp tea towel as an aid. Leave rolled up tightly until cooled

Unwrap, flatten gently and spread with jam. Roll back up without the paper

Slice to serve (with whipped cream and fresh summer berries)