Heat oven to 180C/160C fan/gas 4.
Gently heat the prunes and Marsala
over a low heat until hot. Remove
from the heat and leave for about
1 hr or until the prunes have absorbed
almost all of the liquid. Whizz the prunes
and any remaining booze in a food
processor until roughly chopped.
Butter and line the base of a 20cm
springform tin. Dust with cocoa,
tip out any excess and reserve.
Melt the butter and chocolate in
a heatproof bowl set over a pan
of barely simmering water. Stir
in the prune mix.
Whisk the sugars, 2 eggs and 2 egg
yolks until pale, thick and doubled in
volume. Fold the chocolate mixture and
vanilla into the egg mixture, then sift over
the ground almonds, flour and remaining
cocoa. Fold until everything is combined.
Whisk the egg whites until stiff and
gently fold into the mixture. Spoon into
the prepared tin and bake for 20-25 mins
or until a light crust has formed. Allow to
cool in the tin – it will sink and crack as
it cools. Remove from the tin and dust
with cocoa before serving.