Whip the cream cheese smooth using the paddle attachment of your stand mixer or an electric hand mixer.

Introduce the butter to the cream cheese, one chunk at a time, while continuing to mix at LOW-MED speed.

With the mixer still running, slowly add the granulated sugar to fully incorporate it without causing graininess.

Add the salt and vanilla extract (don't forget to scrape down the sides and bottom of the bowl so that all the cream cheese is well mixed.)

Give the cream cheese a final high-speed mix for 30 seconds to a minute, until all the sugar has dissolved.