In a bowl, add butter, sugar ,cocoa powder and salt.
On a double broiler, place it in a way that the bowl is not touching the water.
Mix it every now and then, until the butter and sugar melt and everything comes together.
Once the batter cools down, add Vanilla Extract. Now add eggs, mix them thoroughly in the batter. Now add quinoa flour and mix it well until the flour is mixed properly in the batter
Pour the batter in the cake pan lined with a parchment paper.
To give a marble look keep a couple of tablespoons of chocolate brownie batter aside.