Preheat the Oven: Preheat the oven to 350°F (177°C) so it is ready when the batter is prepared.
Prepare the Pan: Grease and flour an 8-inch square pan, or line it with parchment paper. A metal baking pan is recommended for more even baking.
Melt the Butter: Place the unsalted butter in a small saucepan and melt it. Keep the butter hot, as it will be combined with the sugar and cocoa powder in the next step.
Combine the Cocoa Mixture: In a large mixing bowl, combine the hot melted butter, granulated sugar, cocoa powder, and salt. Stir thoroughly with a spatula or wooden spoon until combined.
Add the Wet Ingredients: Whisk the oil, room-temperature eggs, and vanilla extract into the butter mixture until the mixture is smooth.
Add the Flour: Add the spooned-and-leveled flour and stir gently with a spatula just until incorporated. Avoid overmixing, as excessive mixing can make the brownies cakier.
Fold in the Chocolate Chips: Gently fold the semi-sweet chocolate chips into the batter until they are distributed throughout.
Fill the Pan: Transfer the brownie batter to the prepared 8-inch square pan and spread it into an even layer.
Bake the Brownies: Place the pan in the preheated 350°F (177°C) oven and bake for about 25 minutes, until the edges look dry while the center remains slightly soft and underdone.
Cool the Brownies: Remove the pan from the oven and allow the brownies to cool before cutting.
Slice and Serve: Cut the cooled brownies into 12 bars and serve.
