Tiramisu Cake

For the sponge:

little softened butter, for greasing

large free-range eggs

caster sugar

self-raising flour

For the filling:

instant coffee granules

boiling water

brandy

x 250g (9 oz) tubs full-fat mascarpone cheese

double cream

icing sugar, sifted

dark chocolate (36% cocoa solids), grated

For the decoration:

dark chocolate, (70% cocoa solids), finely chopped

cocoa powder