Preheat the oven to 350 degrees and spray a 9x13 baking pan with non-stick cooking spray.

Combine the softened butter, sugar, brown sugar, vanilla extract and large eggs. Mix well.

Slowly fold in the unsweetened cocoa powder until it is mixed into the brownie batter (see photo).

In a smaller bowl, combine the flour and baking soda. Slowly mix into the brownie batter.

Fold in the 6 oz of chocolate chips into the brownie batter.

Pour the mixture into a 9x13 baking pan.

Coarsely chop the large dark chocolate candy bar and sprinkle on top of the brownie batter into the baking pan (see photo).

Bake 35-40 minutes at 350 degrees. Insert a toothpick around 35 minutes. If it comes out clean, the brownies are done.

Remove from the oven and allow the brownies to cool before cutting into squares.