In a small bowl, combine baking mix, sugar and cocoa.
Stir in milk and vanilla.
Spoon into two greased 8- or 10-oz. custard cups. For topping, combine the brown sugar and cocoa in a bowl.
Stir in boiling water.
Pour over batter.
Bake at 350 degrees F for 25 minutes or until a toothpick inserted in the cake layer comes out clean.· 25m
Top with ice cream or whipped cream if desired.