Preheat and prepare: Set your oven to 170°C (fan-assisted). Line a 20cm square baking tin with baking parchment, leaving some overhang on two sides — this will become your handle for lifting the baked brownie out cleanly.

Melt the butter and sugar together: Place the butter cubes and caster sugar in a medium saucepan over a low heat. Stir gently with a wooden spoon as the butter melts. You’ll know it’s ready when the mixture looks like a smooth, glossy syrup and feels warm to the touch — about 3 to 4 minutes. Do not let it bubble or boil.

Sift in the cocoa powder: Remove the saucepan from the heat. Sift the cocoa powder over the butter-sugar mixture and stir until fully incorporated. The batter will look thick, dark and slightly grainy at this stage — that’s perfectly normal.

Add the eggs one at a time: Crack the first egg into the saucepan and stir vigorously until it disappears into the mixture. Repeat with the remaining two eggs. The batter should transform into a thick, shiny paste that smells intensely of chocolate. Add the vanilla extract and stir once more.

Fold in the dry ingredients: Sprinkle the flour and salt over the top. Using a gentle folding motion, incorporate the flour until you can no longer see any white streaks. The batter will be stiff and slightly glossy — avoid overmixing, or the brownies will turn cakey. If using chocolate chips, fold them in now.

Bake until the edges pull away: Scrape the batter into the prepared tin and spread it evenly with a spatula. Bake on the middle rack for 20 to 22 minutes. At the 20-minute mark, the centre should still look slightly wet and the edges will have started to pull away from the sides of the tin. The top will have a delicate, papery crust that cracks when you tap it gently.

Cool completely before slicing: Remove the tin from the oven and place it on a wire rack. Allow the brownies to cool in the tin for at least 30 minutes — this step is crucial for that fudgy texture. Once cool, lift the block out using the parchment overhang and slice into 16 even squares with a sharp knife, wiping the blade clean between cuts.