Break the dark chocolate into small, even pieces. Place the chocolate and butter into a saucepan.

Melt them slowly over a very low heat. Stir the mixture until it is smooth and glossy.

Remove the pan from the heat and let it cool. Add the caster sugar and stir it in well.

Whisk the eggs in a separate small bowl. Pour the eggs into the chocolate mixture and stir.

Add the vanilla extract to the pot now. Sift the flour and cocoa powder over the top.

Fold the dry ingredients in using a large spoon. Stop mixing once you see no more white flour.

Stir in your chocolate chips for extra texture. Pour the thick batter into your prepared baking tin.

Smooth the top with the back of your spoon. Bake for about twenty-five minutes in the middle rack.

The center should still have a slight wobble. Let the brownies cool completely in the tin.