COMBINE evaporated milk, sugar, butter and corn syrup in medium, heavy-duty saucepan. Bring to a boil over medium heat, stirring constantly. Reduce heat to low; cook, stirring constantly, for 3 minutes. Remove from heat. Stir in morsels and vanilla extract until thickened and smooth.
SERVE over ice cream or cake. Store leftover sauce in refrigerator; reheat before serving. If needed, add water to thin to desired consistency.
Recipe makes approximately 3 cups.