Instructions

• Preheat oven to 375°F. Lightly grease a 9-by-13 pan and line the bottom and sides with parchment paper. Place the butter into a small saucepan, and heat the mixture over medium heat. Stir every few minutes and watch it closely to prevent it from browning. While the butter is melting, put the white chocolate into a heatproof bowl. When the butter is melted, pour it over the chocolate, and stir gently until every piece of white chocolate has melted into the butter.
• In a large mixing bowl, combine the light-brown sugar, granulated sugar, salt, eggs and vanilla. Use a hand mixer to beat vigorously for 1 minute, until the mixture is pale in color and very creamy-looking. It is important to beat the eggs and sugar really well, because this is how you get a shiny, flaky top layer on your brownie.
• Add the melted chocolate and butter to the egg mixture, and whisk until everything is combined. Add the flour, and use a spatula to incorporate it, mixing just until no dry bits of flour remain.
• Transfer the batter to the prepared pan, and smooth the surface. Gently rap the pan on the counter to burst any air pockets in the batter. Scatter the chopped chocolate over the top, and gently press it in a little (most will sink into the batter).
• Bake for 10 minutes on the center rack of your oven, rotate the pan, and continue baking until a cake tester or toothpick inserted in the center comes out with very moist crumbs still clinging to it, about 15 minutes longer. The edges will show some browning and wrinkling, and the center will still appear a bit unset. If you have beaten the egg mixture enough, there will be a wonderful shiny surface to the brownies.
• Remove the brownies from the oven, and allow them to cool in the pan. Eat immediately, or, if you enjoy a chewier brownie, put the pan in the freezer for ½ hour. Cutting the brownies while they are very cold will produce a densely packed, chewy texture and clean cuts. Store them in an airtight container at room temperature for 1 week or in the fridge for 2 weeks.