Melt butter in a large saucepan.  Stir in sugar, corn syrup and water. 

Bring to a full boil over medium-high heat.  Add condensed milk, stirring constantly. Bring to a full boil for two minutes. Remove from heat and add vanilla.  Serve immediately.

Delicious drizzled over apple pie, bread pudding or as a dipping sauce for fruit.

Recipe tip:  Prepare ahead and reheat in microwave.  If sauce seems too thick, stir in 1 to 2 tablespoons water or milk.