1 1/2 c. sugar
2 tbsp. flour
3/4 c. cold water
1/2 c. plus 1 tbsp. cocoa
3 tbsp. butter
3 tbsp. butter
1 tsp. vanilla

Mix flour and sugar in a heavy saucepan. Blend in water. Heat, stirring constantly over moderate heat, until boiling and thickened. Reduce heat to low, stir in cocoa and then butter until smooth. Beat in butter and vanilla. Cool slightly, beating now and then. Wait until you can't stand it any more and serve over ice cream or anything.