Prepare a 7x7-inch baking pan by lining it with parchment paper.

In a mixing bowl, combine the melted butter, brown sugar, white sugar, and salt. Mix until well combined.

Add the eggs and cooking oil. Mix until smooth.

Using a strainer, sift the all-purpose flour and cocoa powder directly into the bowl.

Add the chopped semi-sweet chocolate.

Fold the batter gently until everything is incorporated. Avoid overmixing to keep the brownies soft and fudgy.

Transfer the batter into the prepared baking pan.

Spread the batter evenly and tap the pan gently on the counter to remove large air bubbles.

In a preheated oven, bake at 180°C (356°F) for approximately 30 minutes.

Allow the brownies to cool completely before slicing into serving pieces.