1. Line a 22x14cm loaf pan with plastic wrap, leaving enough overhanging on the sides to fold over the top later. Place the raisins in a small bowl, warm the rum gently in a small saucepan until hot, remove from the heat before it gets to boiling point. Pour the warmed rum over the raisins and set aside to soak for 30 minutes, then strain the raisins and reserve the remaining rum. 
2. Add the cream to a large bowl, whip with electric beaters until stiff peaks form, set aside. 
3. Melt the dark chocolate dotties in short bursts in the microwave, or in a bowl suspended over simmering water, stir until chocolate is smooth, set aside to cool a little. 
4. In a separate bowl add the egg yolks and sugar, whisk with electric beaters until thick and bubbly. Place the bowl over a saucepan of gently simmering water, do not allow the water to boil and ensure that the bottom of the bowl does not touch the water. Using electric beaters or a hand whisk, continue to whisk the mixture until it is pale, has doubled in size and forms a trail off the whisk, this will take about 5 to 8 minutes, and will be quicker if using electric beaters. 
5. Remove the bowl from the heat, slowly add the reserved rum and vanilla extract, whisk for a few more minutes until mixture has cooled a little. Pour in the melted chocolate and whisk until just incorporated. Fold in the whipped cream a third at a time until fully mixed in. 
6. Fold through the rum-soaked raisins and the finely chopped Koko Black Christmas Pudding chocolate until evenly distributed. 
7. Pour the mixture into the prepared pan and smooth out the top. Fold overhanging plastic wrap gently over the top. Freeze for a minimum of 6 hours, preferably overnight.
8. To make the ganache topping, place dark chocolate dotties in a bowl, heat cream until it just reaches simmering point, do not let it boil. Remove from heat and pour over the chocolate dotties. Leave to sit for a few minutes and then whisk to combine.
9. To serve, open the plastic wrap and invert the semifreddo on to a serving plate, carefully remove the remaining plastic wrap. Drizzle with chocolate ganache and top with chopped Koko Black Milk Chocolate Christmas Pudding chocolate. Serve in slices. 

Note: If you would like a smooth finish, run a hot butter knife or metal spatula along the surface of the semifreddo before decorating.