Pour the melted butter into a large mixing bowl, then pour in the sugar.

Mix the sugar and butter until well combined, then start adding in the eggs, but one egg at a time.

Next, add in the unsweetened cocoa, and mix until well incorporated.

Gradually add the flour into the bowl, then add in the vanilla extract.

Mix the brownie mix until it is smooth, and lump free.

Spray a 8 x 8 pan with baking spray ( you can also use parchment paper).

Pour in the brownie batter into the pan, and smooth it out to make sure it's even.

Bake the brownies on 350 F for about 25 - 30 minutes.

Remove the brownies from the pan, and place it on a cooling rack.

Once the brownies reach room temperature, cut them, and serve.