Preheat oven to 350º
Into large bowl, measure flour, ⅔ c. sugar, ½ tsp. salt, milk, butter, chocolate, baking powder and vanilla.
Beat ingredients with electric mixer on low speed until just mixed.
Increase speed to medium and beat 4 min., scraping bowl occasionally. (Batter will have curdled appearance.)
Pour into a 9x9 in. baking dish
In a medium bowl, combine ½ c. sugar, ¼ tsp. salt, brown sugar and cocoa.
Sprinkle mixture over batter.
Pour 1½ c. boiling water over all. DO NOT STIR.
Bake 60 min.
Batter will separate into cake and sauce layers. Cool slightly.
While warm, spoon into dessert dishes and top with vanilla ice cream.
Spoon any additional sauce from pan onto each serving.