1. Preheat and Prepare the Baking Pan

• Preheat the oven to 350°F (175°C).
• Line an 8×8-inch baking pan with parchment paper, leaving an overhang for easy removal.
• Grease the parchment lightly with butter or non-stick spray.

2. Melt the Butter and Chocolate

• In a heatproof bowl, melt butter and dark chocolate together using a double boiler or microwave in 30-second intervals (stirring in between).
• Let the mixture cool slightly while preparing the other ingredients.

3. Mix the Wet Ingredients

• In a large bowl, whisk together granulated sugar, brown sugar, and eggs until light and fluffy (about 2 minutes). This step helps create a crackly top.
• Stir in the vanilla extract and melted chocolate mixture, mixing until smooth.

4. Sift the Dry Ingredients

• In a separate bowl, whisk together cocoa powder, flour, baking powder, and salt.
• Gradually fold the dry ingredients into the wet mixture, stirring until just combined. Do not overmix.

5. Fold in the Chocolate Chunks

• Gently stir in the semi-sweet chocolate chunks and milk chocolate chips.
• If adding nuts or caramel swirls, fold them in at this stage.

6. Bake the Brownies

• Pour the batter into the prepared pan and spread evenly.
• Bake for 28–32 minutes or until the center is set but still slightly soft (a toothpick should come out with a few moist crumbs).
• Remove from the oven and let cool in the pan for 15 minutes before transferring to a wire rack.

7. Cool Completely & Slice

• Allow brownies to cool for at least 1 hour before cutting for cleaner slices.
• Slice into 16 squares and serve!