Confirm temperature of ingredients: press your finger firmly into the cream cheese block — it should give easily and leave an indent.
Beat the room-temperature cream cheese in a mixing bowl until completely smooth and lump-free.
Add the room-temperature butter and beat together on medium speed until fully combined and fluffy.
Sift in the powdered sugar in two additions through a fine mesh sieve, starting on low speed with each addition.
Mix to the right consistency: after all the sugar is in, beat on medium speed for a final 60 seconds. Add vanilla and salt, mix briefly.
Use immediately for spreading onto a cooled cake, or chill 15 to 20 minutes before piping.