Preheat oven to 350°F and line an 8" or 9" square baking dish with parchment paper. Leave an overhang on the parchment for easy removal and clean up.
In a large bowl, whisk together the melted butter and both sugars.
Add in the eggs and vanilla extract and whisk until completely combined and light brown in color.
Shift the flour, cocoa powder, and salt together. Use a rubber spatula or wooden spoon to combine with the wet ingredients.
Fold in chocolate chips or other ad ins if desired.
Pour batter into the prepared baking dish and bake approximately 25 minutes.
Let the brownies cool at least 30 minutes before cutting.