Classic Chocolate Brownies

Preheat the oven to 350°F (350°F) and place a rack in the middle of the oven.

Line an 8 × 8‑inch (20 × 20 cm) baking tin with parchment paper and lightly grease the paper.

Set a heat‑proof bowl over a pot of simmering water (double boiler) and add the dark chocolate and butter; melt, stirring constantly until smooth, then remove from heat.

In a separate large bowl, combine the granulated sugar, brown sugar, and eggs. Beat with an electric mixer on medium speed until the mixture becomes pale, thick, and roughly doubles in volume, about 3–4 minutes.

Add the salt and vanilla extract to the egg‑sugar mixture and stir just until incorporated.

Pour the melted chocolate‑butter mixture into the egg mixture and fold gently with a spatula until fully combined, being careful not to deflate the batter.

Sift the all‑purpose flour and cocoa powder over the batter in two batches, folding each addition gently until just incorporated; the batter should be thick but still glossy.

Fold in the dark chocolate chunks evenly throughout the batter.

Transfer the batter to the prepared tin, spreading it into an even layer with the spatula.

Bake for 25–30 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs but no wet batter. Remove from the oven and let the brownies cool completely in the tin before lifting out the parchment and cutting into 12 squares.