Cream the softened butter with the paddle attachment until smooth. Add in your softened cream cheese and continue creaming on low until fully incorporated and smooth.
Slowly add in powdered sugar one cup at a time, letting fully incorporate before adding the next cup. Add in vanilla and salt. Mix at low for 5-6 minutes until smooth.
For a whiter buttercream, add white food coloring. Store leftover buttercream in the fridge for up to a week or freeze up to 6 months.
Notes
This buttercream cannot be left out for more than 4 hours.