For the Budino:

1. In a small bowl, combine the milk and heavy cream. In a medium pot over medium heat, mix in the brown sugar, water and salt.
2. Cook until sugar is melted and smells caramelized (color should be dark brown), around 10-12 minutes. Next, add in the cream mixture and whisk until it begins to boil.
3. In a separate bowl, whisk the egg and cornstarch. Slowly, add one cup at a time of the butterscotch mix. Continue whisking and adding the rest of the mix until you get a thick custard-like texture.
4. If using rum, remove the mixture from the heat and whisk it in. Strain the custard using a mesh strainer and divide among 4 serving cups (glass preferred). Cover with lid and refrigerate.

For the Caramel Sauce:

1. In a medium saucepan over medium-low heat, combine the heavy cream and vanilla and bring to a simmer. Add in the butter and turn off the heat while it melts. Set aside.
2. Combine the brown sugar, heavy cream and butter in a small sauce pan over medium heat. Whisk until it thickens, about 5-7 minutes. Whisk in the vanilla and cook for another 2 minutes. Allow to cool and refrigerate until ready to use.

Assembly:

1. Top each budino with 2 tablespoons of caramel sauce, whipped cream, and a pinch of sea salt flakes.