- In a heavy saucepan, bring the sugar, brown sugar, corn syrup, and the Scotch to a boil, stirring to dissolve the sugar. Attach a candy thermometer in the centre of the pan and simmer over medium heat without stirring until the thermometer reads 121 °C (250 °F).
- Remove the saucepan from the heat and gradually stir in the cream. Stir in the butter and vanilla, whisking until the sauce is smooth. Let cool. Store in an airtight container at room temperature.
It may happen that the butterscotch sauce hardens on contact with the cream. If so, return the saucepan on the stove and stir over medium heat until it dissolves.
Enjoy it on ice cream, butter cake, chocolate cake, fruit skewers, bananas, grilled pineapple slices... there is no limit to serve butterscotch sauce.