
Start by buttering your pudding basin very well with a little extra butter. If making your holly, do it now so it can dry before using. Roll three small red balls and stamping out three green leaves with a plunger cutter then press gently together. Set aside until needed.
Place the trivet inside the Instant Pot inner pot and sit the pudding on top. Pour in enough boiling water to come about 1 inch below the foil. Put the lid on, leave the vent open and press Steam, setting a timer to 20 minutes (it wont countdown with the valve open).
When the timer sounds to indicate steaming has finished, press Cancel, lose the valve then set it to Manual High for 25 minutes. NPR for 20 minutes* before removing the pudding. Allow it to stand for at least 10 minutes before running a plastic knife around the edges and releasing it only a serving dish.
Place the chocolate and cream in a microwave proof bowl and zap for 30 seconds at a time on medium heating, stirring in between to mix. When just melted, beat really well with a small whisk and if using, add Advocaat to taste. Any more than 1 tbsp and it will be a runny pouring sauce rather than thick and spreadable.
Whisk again and chill in the fridge for 20 minutes before spreading on top of your pudding. The pudding retains heat very well so try to wait until serving before topping the pud with the ganache so it doesn't completely melt.
*= this is an extremely forgiving pud. It can be left in the Instant Pot to keep warm until needed for up to 2 hours and will still be delicious and moist. You can make the ganache and leave it at room temp instead as soon as you have set the IP up to steam and by the time you serve, 2-3 hours later, it will be a spreadable texture.
It also keeps up to 2-3 days. Just allow it to cool completely, cover in clingfilm and reheat in the microwave when needed. One of two 30 second zaps on high should do it.