Place the chopped chocolate in a heatproof bowl.

In a pot, warm the cream until bubbly around the edges. Pour over the chocolate and stir until the chocolate has fully melted and you have a thin, smooth ganache. Set aside.

In the same pot add the milk, sugar, sea salt and black cocoa. Whisk to combine then cook over medium heat while whisking until the sugar and cocoa granules dissolve, about 5-7 minutes.

Add the ganache to the pot and whisk mixture together until well combined. Remove from heat and stir in vanilla. Check that salt/vanilla is to your taste.

Pour base into a bowl through a fine mesh sieve, to catch any unmixed lumps. Cover the bowl and set in fridge overnight or for at least 8 hours. Freeze ice cream machine bowl, if using.

The next day churn the ice cream according to machine instructions.