Heat oven to 180C/160C fan/gas 4.
Lightly butter and line the bases of
2 x 18cm sandwich tins with baking
paper. Whisk the eggs and sugar until
light and fluffy, about 5 mins with a
tabletop mixer or 10 mins using an
electric hand whisk. The mixture will
have increased greatly in volume and
be thick enough to leave a trail on the
surface when the whisk blades are lifted.
Sift the flour, cornflour, cocoa and
baking powder over the surface and fold
in gently using a large metal spoon.
Divide between the tins, gently spreading
the mixture to the edges, then bake for
15-20 mins until the cakes are well risen,
have begun to shrink away from the sides
of the tins and spring back when gently
pressed. Leave to cool in the tins for
5 mins, then turn out onto a rack.
To decorate, microwave the chocolate
and coffee together on Medium for
20-30 secs until the chocolate has
melted. Gently stir until smooth, then
cool slightly. Beat the soft cheese with
the yogurt and icing sugar until smooth,
then spoon half the mixture into a small
bowl stir in the melted chocolate and set
aside. Place one cake on a serving plate
and spread with the yogurt mixture.
Cover with the other cake, then spread
the chocolate yogurt mixture over the top.
To finish, microwave the 15g chocolate
on Medium for about 20 secs until
melted. Stir gently until smooth, then
drizzle all over the cake.