Add cream to the bowl of your mixer. Using the whisking beater, beat the cream to stiff peaks.
In a large bowl, combine the condensed milk and the vanilla.
Fold in the whipped cream. Set aside in refrigerator.
In a saucepan, combine brown sugar, cream and butter.
Stir to combine. Cook on medium heat until sugar is melted.
Lower heat and let cook for 5 minutes not stirring.
Once everything is combined and thickened, remove from the heat and place in a jar to cool.
Line a loaf pan with parchment paper.
Spoon half of the ice cream base into the loaf pan and spread until even.
Drizzle the cooled butterscotch sauce over the top of the ice cream.
Top with the rest of the ice cream base.
Drizzle the top with the butterscotch sauce.
Take a spoon and swirl the sauce through the ice cream then cover with plastic wrap and place in the freezer for 3 or more hours until set.
Once the ice cream hardens serve on cones or in a dish.