Preheat the oven to 350F, and line an 8x8 baking pan with parchment paper then set aside.
In a large microwave-safe bowl, melt the butter and the white chocolate together in 30-second increments, mixing in between every time.
Whisk in the granulated sugar, egg, egg yolk, and vanilla extract until light and fluffy.
Fold in the flour and salt, pour into the 8x8 baking pan, and bake for 23-25 minutes or until a toothpick inserted in the center comes out with a few crumbs. Let the brownies cool down fully before slicing into them and enjoying.