Blum's Hot Fudge Sauce

This has been a family tradition since before I was born. It is absolutely delicious warm over ice cream, room temperature as a frosting or to just eat by the spoonful by itself or with bananas and strawberries. It is the topping we use for cream puffs and the frosting on our sour cream chocolate cake.

4 (1 oz) squares of unsweetened chocolate
1 lb unsifted powdered sugar
1 12 oz can evaporated milk

Put chocolate, powdered sugar and evaporated milk into a double boiler. Barely stir at the beginning with a spoon or fork and then cook without stirring for at least 15 minutes or longer (to allow the starch to turn into sugar). Pour into blender (do not scrape the edges with a spatula, just let the ingredients drip into the blender and discard what doesn't come on its own - to avoid crystalization) and add:

1/2 c butter
1/2 tsp salt
1 tsp vanilla

Blend until smooth.

When using as a frosting allow to cool before using and use an extra cup or more of powdered sugar into the double boiler.