Instructions:

1. Preheat the Oven: Preheat your oven to 175°C (350°F). Grease a square baking pan with melted butter and line it with parchment paper for easy removal of the brownies later.
2. Melt Chocolate and Butter: In a heatproof bowl, melt the dark chocolate and unsalted butter together. You can do this in a microwave in 30-second bursts, stirring between each burst, or over a double boiler on the stove. Allow the mixture to cool slightly.
3. Whisk Eggs and Sugars: In a separate bowl, whisk together the eggs, sugar, and brown sugar until the mixture is light and fluffy.
4. Combine the Mixtures: Gradually fold the melted chocolate and butter mixture into the egg and sugar mixture. Be gentle to keep the air in the egg mixture.
5. Add Dry Ingredients: Sift in the all-purpose flour and cocoa powder, gently folding them into the mixture until just combined. Avoid overmixing.
6. Add Chocolate Chunks (Optional): If you like extra gooey and chocolatey brownies, fold in chunks of dark chocolate at this stage.
7. Bake: Pour the batter into the prepared pan, smoothing the top with a spatula. Bake for about 25-30 minutes, or until the top is set and a toothpick inserted into the center comes out with a few moist crumbs.
8. Cool and Serve: Let the brownies cool in the pan, then lift them out and cut them into squares. For cleaner cuts, use a sharp knife and clean it between cuts.
9. Serving Suggestions: These brownies are perfect on their own, or you can serve them warm with a scoop of vanilla ice cream for an extra treat.

Enjoy your delightful and chocolaty fudge brownies!