Preheat your oven to 350°F (175°C). Grease an 8x8 inch baking pan with butter or non-stick spray, and line with parchment paper, leaving an overhang on two sides for easy removal. This will help you lift the brownies out later.

In a large, microwave-safe mixing bowl, melt the unsalted butter. Add the granulated sugar and packed light brown sugar to the melted butter. Whisk vigorously for about 1-2 minutes until well combined and glossy. This step is crucial for achieving a crackly top on your brownies!

Add the eggs one at a time, whisking well after each addition until fully incorporated into the sugar mixture. Stir in the vanilla extract. The mixture should appear smooth and slightly thickened.

To the same bowl, add the all-purpose flour, unsweetened cocoa powder, salt, and baking powder. Switch from the whisk to a rubber spatula. Gently fold the dry ingredients into the wet ingredients until just combined. Be careful not to overmix; a few small streaks of flour are acceptable.

Gently fold in 1 cup of semi-sweet chocolate chips until they are evenly distributed throughout the batter.

Pour the brownie batter into the prepared baking pan and spread it evenly with your spatula. If desired, sprinkle a few extra chocolate chips on top for added visual appeal. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out with moist crumbs attached (not wet batter). The edges should look set, but the center might still be slightly jiggly, which is perfect for fudgy brownies.

Remove the pan from the oven and let the brownies cool completely in the pan on a wire rack. Cooling is essential for achieving fudgy brownies that hold their shape when cut. Once fully cooled, use the parchment paper overhang to lift the brownies out of the pan and cut them into 16 squares.