In a small bowl, combine one cup brown sugar, flour, 3 tablespoons cocoa, baking powder and salt. in another bowl, combine the milk, butter, and vanilla, stir into dry ingrediants just until combined. spread evenly in a 3-qt slow cooker coated with some cooking spray. sprinkle with chocolate chips.
In a small bowl, combine the rest of the brown sugar and cocoa, stir in boiling water, pour over batter do not stir. cover and cook on high 4 hours or until a toothpick stuck in center comes out clean. serve warm with some ice cream on top ummmm