Melt the white chocolate and butter

• Melt the white chocolate with the butter in a saucepan over low heat until smooth.
• Remove from the heat and let cool slightly.

Make the batter

• Whisk the granulated sugar, brown sugar, eggs and vanilla extract into the melted chocolate mixture until pale and glossy.
• Fold in the flour and salt until just combined.

Bake

• Pour the batter into a lined square baking pan and spread evenly.
• Bake at 175 °C until the top is crinkled and a toothpick comes out with moist crumbs.

Cool and cut

• Let the brownies cool completely in the pan.
• Cut into squares and serve.