Place the butter and cream cheese in the bowl of a stand mixer fitted with a paddle attachment and beat on medium speed until smooth, about 1 minute.
Reduce the speed to low, slowly add confectioners, and beat until fully incorporated and smooth, about 3 minutes. Stop the mixer and scrape down the paddle and sides of the bowl with a rubber spatula.
Add vanilla and salt. Mixing completely.
Turn mixer to high and beat until light and fluffy.