Preheat oven to 350°F (177°C). Line a 9x13-inch baking pan with foil, making sure to leave some overhang for easy removal, spray the foil well with nonstick cooking spray, and set aside.
In a large mixing bowl, whisk together the melted butter and sugar until well combined, then whisk in the eggs and vanilla extract until fully combined.
Sift in the cocoa powder, flour, and salt and continue whisking until just combined, stopping to scrape down the sides of the bowl as needed.
Pour the batter into the prepared baking pan and spread it around into one even layer. Bake at 350°F (177°C) for 26-32 minutes or until a toothpick inserted into the center comes out clean with just a few moist crumbs.
Remove from the oven and allow to cool before slicing into bars.
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Notes
Store brownies in an airtight container at room temperature for up to 4 days.Freezing instructions: Brownies will freeze well for up to 3 months. Thaw overnight in the refrigerator and bring to room temperature before serving. Room Temperature Eggs: I suggest using room temperature eggs for this recipe. To get your eggs to room temperature quickly, place them in a bowl of warm water and let them sit for 5-10 minutes before using them.