In one bowl whisk the milk together with the whipping cream. In a separate bowl whisk the egg yolks with the cornstarch.
In a saucepan over medium heat whisk the brown sugar, salt, and water. Allow it to cook for about 5min, without stirring. It should get dark brown and start smelling caramelized.
Slowly whisk in the milk and whipping cream mixture. Cook on medium heat until the mixture begins to boil. Once boiling, remove about 100ml of the mixture in a separate bowl, and very slowly whisk in the egg yolks. Keep the egg yolks moving so they don't scramble. Very slowly pour and whisk the egg yolk mixture into the saucepan.
Turn the heat down to low. The pudding will quickly begin to bubble and thicken. Cook and whisk for 1 to 2min over low heat.
Remove it from the heat and stir in the butter, vanilla extract, and the scotch.
Cool the pudding for 5min, then pour it into serving glasses. Refrigerate for 5 to 6 hours or overnight until chilled and thickened.
Serve with caramel sauce or any other toppings of choice.