Preheat oven at 180°C/355°F.

Cut the dark chocolate into small chunks. Place them in a heat proof bowl. Melt them over a simmering water. Add butter and melt them together. Set aside to cool.

In large bowl, add the sugars. Add in the eggs, one at a time. Mix vigorously until the mixture is pale and creamy. This will take about 3-5 minutes, depending how vigorous you are.

Add salt and vanilla, and mix well. Add the chocolate mixture into the egg mixture. Mix until well combined.

Sift in the dry ingredients. Use a spatula to fold in gently, just until the flour disappear. Do not over mix.

Grease a 7x7-inch pan and line 2 parchment papers so that bottom and all sides are covered.

Bake it in preheated oven at 180°C/355°F for 30-35 minutes. Insert a toothpick, if it comes out with sticky batter, that is good because we do not want it over-cooked and not gooey anymore. Of course, if you desire to have it more cooked, then bake it for another 5 minutes or so.

Let it cool completely before cutting it. Insert a knife into a glass of warm water to cut the brownies. Wipe the knife clean for each cut to avoid messiness J

Serve with milk or ice cream!