Preheat the oven @160'c. Line a 8 inch square baking tin with parchment paper and set that aside. 

In a double boiler, melt together the sugar, cocoa, salt and butter until completely smooth and lump free. 

Add vanilla extract and the eggs next. Whisk well until the eggs have been well incorporated.

Next add the flour and mix well at this point. Do not whisk. We don't have to make a fluffy brownie. 

Pour this batter in the ready tin.

Tap the tin a couple of times on the work surface to release any air pockets from the batter. 

Bake this at 160'c for approximately 45-50 minutes or until an toothpick inserted in the center comes out clean or with just a few moist crumbs.

Note that every oven works differently so adjust the temperature.

Do not bake them at a very temperature because they won't cook through and will turn too hard. 

Let them cool down completely once they are baked. Then slice them into squares.

They can be frozen for up to weeks and stored at room temperature in an airtight box for a week.