Start with the caramel, preferably the night before. In a medium saucepan over medium heat melt the sugar. Stirring with a rubber spatula. Lumps will form but keep melting and stirring until it becomes a see through syrup. Be careful not to let it burn.
Add in the butter, it will bubble at this point so be careful. Stir until it completely melts and combines.
Pour the cream in slowly, again, it will bubble. Mix and boil until it reduces slightly. Be careful not to let it catch. Remove from the heat and pour into a bowl. This will last in an air tight container for a couple of weeks in the fridge.
For the Swiss Roll. Preheat the oven to 200°C(180°C fan assisted) and line a swiss roll tray with paper. Whisk together the sugar and eggs for 5-10 minutes until it forms a pale, creamy mixture. The whisk should leave trails.
Sieve in the flour and cocoa powder and mix well. Be careful not to knock the air out but make sure it is well combined with no clumps.
Spread the mixture out evenly into the prepared pan. Using a palette knife to ease it into the corners. Place in the centre of the pre-heated oven for 10 minutes (or until the cake is springy to the touch. I could have baked mine for a minute or so less).
Remove from the oven and allow to cool for a few minutes in the pan, covered with a damp cloth. In the meantime, lay out a large piece of greaseproof paper and dust with cocoa powder. Transfer the cake to this.
While it cools on the new parchment, make the buttercream. Cream the butter until smooth and add the icing sugar. Beat until combined.
Using a palette knife evenly spread the buttercream onto the cooled cake. Top with the caramel, again smooth evenly.
Using the greaseproof paper, slowly roll it up.
Recipe by The Bearded Bakery at http://www.thebeardedbakery.com/baking/cakes/chocolate-swiss-roll/