Preheat the oven to 375º F (180º C). Line a square pan of about 1.2 inches (23 cm) with parchment paper. 2
In a big bowl, sift together the flour, cocoa powder and confectioners sugar. Add in the white and brown sugar and salt and combine using a spoon.
Ina different medium size bowl, add the eggs with the melted butter and vanilla extract. Beat using a hand whisk for 1 minute until it is all well integrated.
Pour the liquid ingredients onto the liquid ones and mix using a rubber spatula for 30 seconds. You will get a really thick batter, almost like a cookie dough, that's what we want.
Pour the batter into the pan and even it out. Bake at 375º F (180º C) for about 40 minutes until a wooden stick comes out clean when inserted, or almost clean.
Take the brownies out of the oven and let them cool down for 20 minutes before cutting them out. Then cut 16 equal pieces.