In the bowl of a stand mixer fitted with the whisk attachment or hand mixer, beat cream cheese and butter on medium speed until mixture is light and fluffy, 4 to 5 minutes.
Scrape down sides of bowl, and add 3/4 cup powdered sugar and salt. Beat on low speed until mixture is smooth, about 1 minute.
Add sour cream and whole milk, beat on low speed 1 minute.
Add remaining 3/4 cup powdered sugar, and beat on low speed until sugar is completely incorporated.
Scrape sides of bowl, and increase speed to medium-high, whisking until mixture is well combined.
Drizzle glaze on cooled cake.
Enjoy!