Soak the raisins in the dark rum for a couple of hours or overnight to absorb the alcohol. Crush the morning coffee biscuits and palace into a mixing bowl with the cinnamon powder, orange zest and hazelnuts. Place the butter, water, caster sugar, orange juice and cocoa powder in a sauce pan and bring to the boil until sugar and cocoa are melted. Pour over the crushed biscuits mixture and stir well until combined. Press the mixture into a buttered and lined 20cm spring form cake tin and flatten out using a palette knife. Melt the milk chocolate in a bain-marie, whisk in the cream to make a ganache and pour the over the biscuit cake. Sprinkle with extra hazelnuts and allow to set in a refrigerator for approximately 2 hours before serving.