Directions
Preheat the over to 325ºF [165ºC]. Line an 8 in [20 cm] square pan with aluminum foil, covering the bottom, up the sides, and hanging about 1 in [2.5 cm] over the sides.
Melt 1 cup [170 g] of the white chocolate chips and butter together using a hot water bath or the microwave oven. Stir until completely melted and smooth. Remove the bowl from the water if you used a hot water bath and set aside to cool.
In a large bowl, with a hand mixer, beat together the eggs, sugar, vanilla, and salt on high speed until very pale and thick, 2 to 3 minutes. Blend in the cooled melted white chocolate mixture on low speed. Gradually beat in the flour until just incorporated. With a wooden spoon, fold in the remaining ½ cup [85 g] white chocolate wafer, the milk chocolate chips, and dark chocolate chips. Spread the batter evenly in the prepared pan.
Bake for 35 to 40 minutes, or until a toothpick inserted into the centre comes out almost clean. Let cool in pan overnight so the chocolate can set. When ready to serve, carefully use the foil to lift the brownies out of the pan. Place the brownies on a cutting board, discard the foil, and cut them into 1 ½ in [4 cm] squares. Store in an airtight container at room temperature for up to 1 week.
To freeze, cut into four large sections and removed from pan. Wrap sections tightly in plastic wrap. Place the sections in a zip-top freezer bag and push out all the air. Freeze for up to 1 month. Let the wrapped sections defrost in the refrigerator overnight.
This recipe is courtesy of Amy Guittard from her Guittard Chocolate Cookbook.