Preheat oven to 350 degrees.
Combine 1 c sugar, flour, baking powder, salt, and nuts in a bowl.
Add 3 T cocoa.
Combine milk, butter, vanilla, and melted chocolate in another bowl; mix thoroughly.
Add to dry ingredients and beat with an electric mixer until well blended.
Pour batter into a buttered 9 inch pan and set aside.
Combine remaining sugar, brown sugar, and remaining cocoa in a mixing bowl.
Slowly whisk in hot water.
Whisk until smooth.
Gently ladle sauce over cake batter to cover completely.
Bake 35 - 40 minutes or until a toothpick inserted in center comes out clean.