Measure your cocoa into a medium saucepan and pour over the boiling water. Whisk to combine and bloom the cocoa - you should be left with a paste consistency.
In a medium bowl, mix together the caster sugar and xanthan gum. This helps disperse the xanthan gum which minimises the risk of it clumping when the liquid is added.
Add the milk, cream and salt to the cocoa mixture and whisk to combine before adding the sugar and xanthan gum mixture. Whisk thoroughly and quickly to help disperse it. I recommend switching to a silicone spatula from here on out to minimise foam and to get in the corners of the pot to keep the xanthan gum from gelling up in one spot.
Add the glucose syrup or corn syrup then transfer the mixture to the stove on a low-medium heat. Cook for 1-3 minutes or just until the sugars have completely dissolved and incorporated. The mixture should be a medium chocolate brown.
Allow the mixture to cool slightly before pouring into your Ninja Swirl 470ml tub (make sure the bottom mechanism is closed first!). Place in the freezer for 24 hours with the lid off. Leaving the lid off can minimise the risk of the mixture forming a hump which can damage the blades of your machine.
When you are ready to eat, process the mixture on the SCOOP and ICE CREAM settings. Using the SWIRL setting will over-process a cream based ice cream.
You can eat the ice cream as scoops or swap the lid and add the nozzle to make soft serve using the lever. There will be some ice cream left in the base of the container if you make soft serve.