Lightly grease an 8-inch square baking pan with cooking oil spray. Line with parchment paper (or baking paper); set aside.
Combine melted butter and sugar together in a medium-sized bowl. Whisk well for about a minute. Add the eggs and vanilla; beat until lighter in color.
Add in flour, cocoa powder and salt. Gently fold the dry ingredients into the wet ingredients until JUST combined (do NOT over beat as doing so well affect the texture of your brownies).
Pour batter into prepared pan, smoothing the top out evenly.
Bake for 20-25 minutes, or until the centre of the brownies in the pan no longer jiggles and is just set to the touch (the brownies will keep baking in the hot pan out of the oven).
For best results let cool until room temperature, but if I’m being real, that NEVER happens.