Preheat your oven to 325°F (163°C). Lightly grease your 8-inch square baking pan and line it with parchment paper, leaving some overhang on the sides.
Sift together the 1 cup all-purpose flour, 1 cup unsweetened cocoa powder, and 1 teaspoon salt into a medium bowl. Set aside.
Using a microwave or stovetop, gently melt the 3 tablespoons unsalted butter. Pour the melted butter into a large mixing bowl, then add 1 cup granulated sugar. Whisk until combined thoroughly.
Crack in the 3 large eggs, one at a time, whisking well after each addition. Then stir in 1 teaspoon vanilla extract.
Gradually fold the sifted flour and cocoa powder mixture into the wet ingredients using a rubber spatula. Mix gently until just combined.
If you’re using chocolate chips, fold in 1 cup semi-sweet chips now.
Pour the batter into your prepared pan and spread it evenly. Bake for 28–32 minutes, or until a toothpick inserted near the center comes out with a few moist crumbs but not wet batter.
Allow the brownies to cool completely in the pan on a wire rack. Once cooled, lift them out using the parchment paper and dust the top lightly with powdered sugar.
Slice into squares and serve as is, or with a scoop of vanilla ice cream for a decadent treat.