Preheat your oven to 180°C (160°C Fan) and line a 9-inch square tin with baking parchment.

Break the dark chocolate into pieces and melt it together with the butter in a heatproof bowl over a pan of simmering water (or in short bursts in the microwave). Once melted, set aside to cool to room temperature.

In a separate bowl, whisk together the eggs and caster sugar with an electric whisk until the mixture is pale, thick, and doubled in volume. You’ll know it’s ready when the mixture leaves a trail for a second or two when you lift the whisk.

Gently pour the cooled chocolate mixture into the whisked eggs and fold together using a spatula – go slowly to keep the mixture light and airy.

Sift the flour and cocoa powder over the chocolate mix and fold it in gently until fully combined.

Fold in the milk chocolate chips, then pour the batter into your prepared tin and level the top.

Bake for 20–25 minutes, or until the top is set with a slight wobble in the middle – this gives that perfect fudgy centre.

Leave the brownies to cool completely in the tin before slicing into 16 squares.