Tip the hazelnuts on a lined baking sheet and roast for 10-12 minutes until golden brown.
Meanwhile pour the milk, cream, half of the sugar(¼ cup) and the salt into a heavy based sauce pan.
Bring to a simmer and then heat gently for 6 minutes. Once hot and combined, remove from the heat and set to once side.
Once the hazel nuts are roasted allow them to cool for 2 minutes and then whilst they are still warm rub them in a clean t-towel or dish towel to remove the skins.
Tip the hazelnuts, remaining brown sugar (¼ cup) and the liquor into a food processor and whizz until you have a smooth paste. This will take quite a while (about 4 minutes)
Scrape all of the hazelnut paste into the cream mixture and place it over a low heat.
Simmer for 5 minutes until the paste has dissolved.
pour the mixture into a bowl or jug and allow to cool. (or place it in your ice cream maker if your model allows for hot liquids)
Once the cream mixture is cold, pour it into the bowl of your ice cream machine and churn according to manufacturers directions.
Serve immediately as soft scoop or freeze until needed.
Remove from the freezer for 5 minutes before you want to serve it.