Put the sugar in a pan and let it melt over medium heat.

When all the sugar has melted, let it caramelise until it turns a very dark amber colour.

Remove from the heat and add the butter and salt. Stir well.

Add the cream and stir (don’t worry if the caramel hardens at this stage because it will melt again once it is heated).

Return the pan to the heat and cook until the caramel reaches 108°C – 226°F on a candy thermometer (this can also be done without a thermometer because the mixture will naturally boil at 100°C – 212°F, so keep it boiling for a few extra minutes).

Add the cream and milk to the caramel and cook over low heat until the salted caramel has completely melted.

Let the mixture cool, then chill it thoroughly in the fridge.

Add the alcohol and mix well. Filter the mixture through a sieve and bottle it.

Keep it in the fridge for a couple of days and shake well before serving cold.