Preheat your oven to 175°C (350°F). Line an 8x8 inch (20x20 cm) baking pan with parchment paper, leaving an overhang on the sides. This will help you lift the brownies out easily later. Lightly grease the parchment paper as well.

In a medium heatproof bowl, combine the 225g (1 cup) of melted unsalted butter and 300g (1 ½ cups) of granulated sugar. Whisk them together until well combined and the mixture is smooth.

Add the 3 large eggs to the butter and sugar mixture, one at a time, whisking well after each addition. Ensure each egg is fully incorporated before adding the next. This helps emulsify the batter.

Stir in 1 tablespoon (15ml) of vanilla extract. Mix until just combined.

In a separate small bowl, whisk together 125g (1 cup) of all-purpose flour, 50g (½ cup) of unsweetened cocoa powder, and ½ teaspoon (3g) of salt. This ensures the dry ingredients are evenly distributed and prevents clumps of cocoa powder or salt in your brownies.

Gradually add the dry ingredients to the wet ingredients. Fold them in gently using a spatula until just combined. Be careful not to overmix; overmixing can lead to tough brownies. Stop mixing as soon as you no longer see streaks of flour.

If using, gently fold in 150g (1 cup) of semi-sweet chocolate chips. Distribute them evenly throughout the batter.

Pour the batter into the prepared 8x8 inch (20x20 cm) baking pan. Spread it evenly using your spatula. The batter will be thick.

Bake for 25-30 minutes at 175°C (350°F). To check for doneness, insert a toothpick into the center of the brownies. It should come out with moist crumbs attached, but not wet batter. If it comes out completely clean, they may be overbaked and will be more cakey. A few moist crumbs indicate a perfectly fudgy center.

Once baked, remove the pan from the oven and let the brownies cool completely in the pan on a wire rack. This cooling process is crucial for the brownies to set properly and develop their fudgy texture. Resist the urge to cut them while warm!

Once completely cooled, use the parchment paper overhang to lift the brownies out of the pan. Place them on a cutting board and cut into 16 squares (4x4 grid). Use a sharp knife and wipe it clean between cuts for neat edges.