Step 1

Preheat the oven to 325°Fahrenheit (165°C) and line a 9x9-inch baking pan with parchment paper. Set aside.

Step 2

In a large microwave-safe bowl, combine 6 ounces of chopped chocolate and the cubed butter. Microwave in 20-second intervals, stirring well between each spin, until the mixture is smooth and fully melted. Set aside to cool

Step 3

In a separate large bowl, beat the granulated sugar, brown sugar, eggs, and yolk until thick and pale.

Step 4

Stir the vanilla extract into the egg mixture. Then, pour in the melted white chocolate and stir until fully incorporated.

Step 5

Whisk the all-purpose flour, salt, and baking powder in a separate bowl until evenly combined.

Step 6

Stir the dry mixture into the white chocolate batter gently by hand with a spatula until about halfway combined. Add the remaining chopped chocolate and stir until just combined.

Step 7

Pour the batter into the prepared baking pan, spreading it out evenly.

Step 8

Bake for approximately 30-35 minutes or until the edges look set and lightly golden. A toothpick inserted into the center should come with just a few moist crumbs.

Step 9

Optional: If desired, press the white chocolate chips on top of the hot brownies. The heat will melt them slightly so they stick.

Step 10

Let the brownies cool in the pan for 10-15 minutes. Then, use the parchment paper to lift the brownies out of the pan to cool completely on a wire rack.

Step 11

Once cooled, slice the brownies into squares and serve. Enjoy!