Preheat your oven to 350°F (175°C) and line your baking pan with parchment paper, leaving some overhang for easy removal later.
In a large mixing bowl, cream together the brown sugar and butter until light and fluffy. This should take about 2-3 minutes. Add the eggs one at a time, mixing well after each addition. Finally, stir in the vanilla extract.
In another bowl, whisk together the flour, cocoa powder, and salt. Make sure there are no lumps to ensure a smooth batter.
Gradually add the dry mixture to the wet ingredients, stirring until just combined. Be careful not to overmix; a few lumps are perfectly fine.
Pour the batter into the prepared baking pan, smoothing the top with a spatula. Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs.
Once baked, remove the brownies from the oven and let them cool in the pan for about 10 minutes. Using the parchment paper, lift them out and transfer to a wire rack to cool completely before cutting into squares.
