Preheat the Oven to 180C
Grease or line an 8 inch square Cake Pan with Baking paper
Melt the Butter on a low heat in a small saucepan or in the microwave (don't let it boil)
In a bowl add the melted butter, sugar and cocoa and stir until fully combined
Add the eggs one at a time, stirring in-between until combined
Add the vanilla and stir in
Finally add the flour and salt (only add salt if you used unsalted butter) stir in until completely combined.
Pour the Brownie batter into the cake tin and smooth out
Bake for 20 minutes or until the brownie starts to pull away from the edges of the tin and a skewer comes out clean. Be careful not to overbake!
Turn out onto a cooling rack to cool completely
Cut into 9 generous squares and serve!