Salted caramel Swiss roll
For the sponge: 90g sugar; 3 large eggs; 1tsp vanilla bean paste or extract; 75g plain flour; 15g cocoa powder; plus extra for dusting; ½tsp baking powder; for the filling: 125g light muscovado sugar, 75ml double cream, 75g butter at room temperature, ½tsp salt.
Preheat the oven to 200C. Grease and line the Swiss roll tin.
Place the sugar, eggs and vanilla into a mixing bowl and whisk using a hand mixer until it has tripled in volume, and clings for a few seconds then drips in a steady stream when the whisk is lifted out.
Sift the flour, cocoa and baking powder over the mix and then gently fold in with a spatula until well incorporated. Carefully pour this into the prepared tin and level off with a spatula, before baking in the preheated oven for eight to 10 minutes, or until evenly risen and the sponge springs back when gently touched.
Remove from the oven. Dust a piece of baking paper with cocoa powder, onto which invert the freshly baked sponge and allow to cool completely.
Meanwhile, make the filling. Place the muscovado sugar and cream into a saucepan and heat over a medium/high heat until the sugar dissolves. This forms your caramel sauce. Allow to bubble for a minute or two, before pouring onto a large plate to cool.
When cool (it’s important that it is completely cool), beat the butter in a bowl then slowly whisk in the caramel sauce until thick and well incorporated, and then add the salt.
Smooth the filling over the cooled sponge, leaving a centimetre or two at one of the shorter ends. Then roll up the sponge along the length, into a tight spiral.