Photo: Jonathan Gregson
Preheat the oven to 180°C (350°F) Gas 4.
To make the roulade, put the eggs, sugar and
vanilla into a large mixing bowl and whisk with
a handheld electric whisk for about 5 minutes,
until the mixture is pale and thick and has
trebled in volume.
Sift the flour, cocoa powder, baking powder
and salt into the bowl and gently fold into the
egg mixture using a large metal spoon, taking
care not to knock out too much air. Carefully
pour the cooled, melted butter around the
edge of the bowl and fold in until there are
no traces of it.
Spoon or pour the batter into the prepared
pan and gently spread level with a palette
knife. Bake on the middle shelf of the
preheated oven for 8–10 minutes, or until
well-risen with a light crust and the cake
springs back when lightly pressed with your
finger. Let the cake cool in the pan for a minute.
Meanwhile, lay a large sheet of baking
parchment on a clean work surface and scatter
with 1 tablespoon caster/granulated sugar.
Carefully turn the roulade out of the pan onto
the sugar-coated paper and peel off the paper
lining. Lay a clean dish towel on top of the
cake and, starting at one of the shorter edges,
roll the cake into a tight spiral with the towel
inside the roll. Set aside until completely cold.
To make the buttercream, melt the chocolate
in a heatproof bowl set over a saucepan or pot
of barely simmering water. Stir until smooth
and set aside.
To make the meringue, put the egg whites,
sugar and salt in a separate heatproof bowl
set over a saucepan or pot of simmering water.
Add 2 tablespoons of water and whisk until the
sugar has completely dissolved and the mixture
is foamy. Continue to cook for about 5 minutes,
until the mixture is warm to the touch, thickens,
turns bright white and will hold a ribbon trail.
Pour the mixture into a large mixing bowl
and beat for about 3 minutes with an electric
handheld whisk, until it has doubled in volume
is thick, stiff, glossy and the outside of the
bowl feels cold to the touch.
Gradually add the butter to the cold meringue
mixture, beating constantly on low–medium
speed, until the frosting is smooth. Using
a large spoon or spatula fold in the melted
chocolate and the chestnut purée/spread.
To assemble the roulade, carefully unroll
the cooled cake and remove the dish towel.
Spoon 4 generous tablespoons of buttercream
onto the cake and spread evenly using a
palette knife. Scatter with the chopped marron
glacé. Using the baking parchment to support
the cake, roll the cake back into a tight spiral
and transfer to a serving plate. Cover the
whole cake with more buttercream, scatter
with chocolate shavings and dust with cocoa
powder to serve.
This recipe is taken from Chocolate at Home by Will Torrent (Ryland Peters & Small, £19.99)