In a bowl, whisk ⅔ cup dark brown sugar, cornstarch, and salt. Set aside.

In a saucepan, heat the cream and milk until just steaming. Add the vanilla bean paste.

Stir the sugar mixture into the cream and continue mixing until sugar is dissolved. Continue stirring over medium heat until milk/cream is very hot, but not boiling.

While milk/cream is heating, whisk together the egg yolks and 1 tablespoon dark brown sugar in a separate bowl.

Gently pour some (like maybe a third) of the hot cream/milk into the yolks. Again, whisk this constantly or you will end up with scrambled egg budino, I promise you.

Pour the tempered egg mixture back into the pan. Keep the heat on medium, stir continuously until super smooth and thickened and creamy. I looked for the first decent-sized bubble to pop up and then I took it off.

Move the saucepan off the heat. Stir in the butter until melted, this will make for a rich and shiny pudding.