01 - Preheat oven to 350°F (175°C). Lightly grease a 9-inch pie pan or an 8×8-inch baking dish to prevent sticking.
02 - In a medium mixing bowl, whisk together melted butter and granulated sugar until smooth. Add all-purpose flour, unsweetened cocoa powder, eggs, vanilla extract, and salt. Stir until the mixture is thoroughly combined.
03 - Fold semi-sweet chocolate chips into the batter if desired for extra richness.
04 - Pour the batter evenly into the prepared pie pan or baking dish. Level the surface using a spatula.
05 - Bake for 25 to 30 minutes until the edges are set but the center remains slightly gooey. A toothpick inserted should emerge with moist crumbs, not dry.
06 - Allow the dessert to cool for 5 minutes prior to slicing. Serve warm, accompanied by vanilla ice cream or freshly whipped cream if desired.