Preheat the oven to 350°F (177°C) and grease a 9×13-inch baking pan or line with aluminum foil or parchment paper, leaving an overhang on the sides to lift the finished brownies out (makes cutting easier!). Set aside.

In a microwave-safe bowl, combine the butter and chopped white chocolate. Melt in 30 second increments, whisking after each, until completely smooth. Whisk in the sugar until completely combined, then whisk in the eggs and vanilla. Whisk in the flour and salt, then fold in the white chocolate chips until combined. Batter will be thick. Spread evenly into prepared pan.

Bake for 30 minutes, covering loosely with aluminum foil halfway through. Test the brownies with a toothpick at the 30 minute mark. Insert it into the center of the pan. If it comes out with wet batter, the brownies are not done. If there are only a few moist crumbs, the brownies are done. Keep checking every 2 minutes until you have moist crumbs. My brownies take 32 minutes.

Remove from the oven and place on a wire rack to cool completely before frosting.

In a large bowl using a handheld or stand mixer fitted with a paddle or whisk attachment, beat the cream cheese and butter together on high speed until smooth and creamy. Add the white chocolate, confectioners’ sugar, and vanilla. Beat on low speed for 30 seconds, then switch to high speed and beat for 2 minutes. Taste, then add a pinch of salt if desired. Spread the frosting on the cooled brownies, then slice and serve.

Cover and store leftover frosted brownies in the refrigerator for up to 1 week, or if the brownies are not frosted, at room temperature for up to 1 week.