Preheat your oven to 180°C (350°F) and line an 8-inch square baking pan with parchment paper, leaving overhang for easy removal.
Gently melt the butter in a small saucepan over low heat until it appears glossy and smooth. Take it off the heat and let it cool slightly until it's warm but not hot to the touch.
In a large mixing bowl, whisk together the granulated sugar and lightly beaten eggs until the mixture is smooth and slightly fluffy. Then, add the vanilla extract and whisk again.
Pour the slightly cooled melted butter into the egg mixture, whisking continuously until fully incorporated and silky.
Sift together the cocoa powder, all-purpose flour, and salt into the wet ingredients. Gently fold the dry ingredients into the wet with a spatula, just until combined—avoid overmixing to keep the brownies fudgy.
Fold in the dark chocolate chunks evenly throughout the batter, ensuring pockets of melty chocolate in every bite.
Pour the batter into your prepared pan and spread it into an even layer with a spatula. Tap the pan lightly on the counter to settle the batter and remove air bubbles.
Bake the brownies for about 20-22 minutes, until the edges are firm and pull away slightly from the pan, and the top has developed a shiny, crackly surface. A toothpick inserted into the center should come out with moist crumbs.
Remove the brownies from the oven and allow them to cool in the pan for at least 15 minutes. Then, transfer to a wire rack and cool completely for about 30 minutes to let the texture set.
Once cooled, lift the brownies out using the parchment overhang and cut into squares. Serve as is or with a dusting of cocoa powder for an extra touch.
