For the Pudding: 

1. PREP: Before you start cooking, you’ll want to get all your ingredients ready. Mix together the cream and milk in a medium-sized bowl and set aside. Then whisk together the egg, egg yolks, and cornstarch in another bowl and set aside.
2. MAKE THE CARAMEL: Add the brown sugar, ½ cup water, and the salt to a large, heavy-bottomed pot. Cook over medium-high heat until the sugar is melted, dark brown, and smells caramelized, 10 to 12 minutes. The mixture will softly boil. That’s ok. You don’t need to stir it.
3. STIR IN THE MILK AND CREAM: Slowly and carefully whisk in the cream and milk mixture and continue whisking. The butterscotch will likely harden up as soon as you add the cold cream mixture but just keep whisking. It will quickly liquify again. Mine took about 2 minutes of constant whisking before it was absorbed. Bring the mixture to a boil and then immediately lower the heat to medium.
4. TEMPER THE EGG MIXTURE: Next, you’ll want to add the egg mixture. But you can’t just dump it into the hot caramel mixture, or you’ll end scrambling the eggs. To avoid this, you’ll want to scoop out 1 cup of the prepared butterscotch and slowly add it to the egg mixture, whisking constantly. When it’s fully incorporated, slowly add the egg mixture back into the butterscotch. Bring to a boil and continue to whisk until the pudding has started to thicken. This should happen pretty quickly (about 2 minutes).
5. STIR IN BUTTER AND BOOZE: Remove from the heat and stir in the butter and rum, scotch or whiskey, if using. Let it cool for about 5 minutes and then strain the mixture through a mesh strainer (to remove any lumps).
6. SPOON INTO RAMEKINS & CHILL: Then pour or spoon into ramekins or glasses. This recipe will fill 10 6-ounce ramekins. Cover with plastic wrap and the chill in the refrigerator for at least three hours until the custard is fully set. 
7. TOP AND SERVE: When ready to serve, top the pudding with salted caramel sauce, a dollop of whipped cream and flaky sea salt.  

For the Salted Caramel Sauce:

1. MELT THE SUGAR: In a medium saucepan over medium-low heat, melt the sugar while stirring constantly stirring. Once the sugar is completely melted, it will look like golden-brown syrup. Be careful not to burn it.
2. ADD THE BUTTER: Once the sugar is melted, carefully add the butter slices. It’s normal for the butter to bubble rapidly when added. Just keep stirring until the butter is melted (about a minute), be careful not to splash yourself.
3. ADD THE CREAM: Next, slowly add the cream. Again, the mixture will bubble up when the cold cream is added. If you notice any clumping (this happens to me), remove the mixture from the heat and whisk until combined.
4. ADD THE SALT: Once the sauce is combined, remove from heat and mix in the salt. Allow it to cool slightly before using.
5. STORAGE: You can store the salted caramel sauce in an airtight container in the refrigerator for up to 1 month. As the mixture cools, it will thicken. Just reheat on the stove or in the microwave when you’re ready to use it.

For Whipped Cream:

1. WHIP THE CREAM: Using a hand mixer or a stand mixer fitted with a whisk attachment, whip the heavy cream, sugar, and vanilla extract on medium-high speed until medium peaks form, about 3-4 minutes.
2. STORAGE: Use immediately or cover tightly and chill in the refrigerator for up to 24 hours.