Preheat your oven to 325°F (170°C).
In a mixing bowl, whisk together the cocoa powder, granulated sugar, and melted butter until smooth.
Add the eggs one at a time, mixing well after each addition.
In a separate bowl, sift together the flour and a pinch of salt.
Gradually fold the dry ingredients into the wet ingredients until just combined. Do not overmix.
Pour the batter into a prepared baking pan and smooth the top.
Bake for 20-25 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
Let the brownies cool completely in the pan before cutting into squares and serving.