- Place the sugar, corn syrup and milk in a saucepan and stir over low heat until the sugar dissolves.
- Bring to a boil, then simmer for 5 minutes.
- In the top of a double boiler dissolve the marshmallows and butter in the 2 tablespoons of water.
- Once the marshmallows are completely melted stir in the hot syrup beating well.
- Add the vanilla.
- The sauce may be reheated in the top of a double boiler.
- Beat well before serving.