Wash and peel the pumpkin, then dice it into 2 inches cubes.
Add the pumpkin to a pot with the water and put to cook until soft. Leave to cool.
Add the pumpkin, dragon stout beer, supligen (or the alternative), condensed milk, vanilla extract, nutmeg and cinnamon to a blender and blend until smooth.
Serve over ice.
Notes
You can use Guinness in place of the Dragon Stout beer.
There are several Supligen alternatives.
I used unsweetened oats milk, which is why I used that amount of condensed milk. If you use Supligen, reduce the amount of condensed milk to prevent making the punch too sweet.