Preheat your oven to 350°F (175°C). Lightly grease a 9x13 inch baking pan and line it with parchment paper, allowing an overhang on the longer sides to make lifting the brownies easier later.

In a large mixing bowl, melt the unsalted butter. You can do this in the microwave (in 30-second intervals) or on the stovetop. Ensure the butter is fully melted but not boiling hot.

Add the granulated sugar and packed light brown sugar to the melted butter. Whisk vigorously for about 1 minute until the sugars are fully dissolved and the mixture is smooth and slightly glossy.

Whisk in the eggs one at a time, ensuring each egg is fully incorporated before adding the next. Continue whisking until the mixture becomes thick, glossy, and noticeably lighter in color, about 1-2 minutes.

Stir in the vanilla extract.

Add the unsweetened cocoa powder, all-purpose flour, baking powder, and salt directly into the same bowl.

Using a rubber spatula, gently fold the dry ingredients into the wet ingredients until *just* combined. Mix until no streaks of dry flour remain, but be careful not to overmix, as this can lead to tough, cake-like brownies.

If using, gently fold in the semi-sweet chocolate chips for an extra layer of chocolatey goodness.

Pour the brownie batter into the prepared baking pan and spread evenly with the spatula.

Bake for 25-30 minutes, or until a toothpick inserted into the center comes out with moist crumbs attached, but no wet batter. The edges should appear set and slightly puffed.

Allow the brownies to cool completely in the pan on a wire rack before attempting to lift them out using the parchment paper overhang. This step is crucial for perfectly fudgy and set brownies.

Once cooled, lift the brownies from the pan, peel off the parchment paper, and cut into 16-20 squares. Serve and enjoy!