I don't know who Aunt Liza was other than someone in my paternal grandfather's family. As a child, this is the only frosting I ever had on my birthday cake. It is very puddingish (is that a word?) and really delicious. My daughter-in-law can never remember what it is called so she asks for "Aunt Sophie's Sauce". lol
In a medium sauepan, mix sugar, cocoa and salt. Stir in water and return to a boil. Mix cornstarch with a little water to form a paste. Add to the boiling mixture, stirring constantly, until mixture thickens. Remove from heat. Stir in butter and vanilla. Let frosting cool before frosting cake.