1. In a bowl, pour the rum over the raisins then cover with plastic wrap. Allow to sit for a minimum of 1 hour.
2. Place the cream into a saucepan and bring to the boil.
3. Add the condensed milk and butter, then stir over low heat until completely combined.
4. Pour the hot mixture over the chocolate and stir until the chocolate has completely melted and incorporated.
5. Add the soaked raisins and any excess rum, then mix to combine.
6. Place plastic wrap over the spread so it touches the surface and allow it to set for 2 hours at room temperature before serving.

NOTE:  The spread is best kept at room temperature, in a cool, dry place for up to 7 days.