In bowl #1: Measure out 1/2 cup white sugar, 4 tablespoons cocoa, brown sugar, toffee pieces and pecans into a bowl. Stir to mix. Set aside for topping.
In a bowl #2: Stir together remaining 1 cup sugar, remaining 3 tablespoons cocoa powder, baking powder, flour and salt. Stir in melted butter and vanilla . Mix until smooth with a mixer. Pour into an ungreased 8 inch square baking pan. Then pour topping from bowl #1 evenly over the batter. Then pour hot water over mixture and DO NOT STIR. Bake in preheated oven.