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.
1 cup (230 grams) unsalted butter, 2 ¼ cups (450 grams) granulated sugar, 4 large eggs, 2 teaspoons vanilla extract
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.
1 cup (85 grams) unsweetened cocoa powder, 1 cup (125 grams) all-purpose flour, ½ teaspoon salt
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.
Video
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.