Put the brown sugar in a medium pot over medium heat and caramelize the brown sugar until it smokes a bit. Add the cream, salt, and 3½ cups of the milk, and scald the mixture. In a separate bowl, whisk together egg yolks, cornstarch and the remaining 1 cup of milk. Temper the egg mixture by adding the hot liquid in ½-cup increments while gradually whisking. Pour the mixture back into the pot and bring to a simmer. Add the butter, scotch, vanilla, molasses, and lemon juice. Strain the pudding, then pour into short glass jars or ramekins. Top with banana slices and marshmallow. You can use a crème brûlée torch to caramelize the bananas and toast the marshmallow. If using a crème brûlée torch, make sure the glass jars or ramekins are heat proof to prevent the glass from shattering.