In a medium mixing bowl, beat the cream cheese and butter together with an electric hand mixer at medium speed until well combined. It's okay if it looks a little crumbly.
12 ounces (340 grams) cream cheese, 3-6 tablespoons (42-84 grams) unsalted butter
Gradually beat in the powdered sugar until totally combined and then beat in the salt and vanilla. If it's firm enough for your needs, frost your cake / cupcakes.
1 cup (120 grams) powdered sugar, pinch salt, 1/2 teaspoon vanilla extract
If you want it firmer, refrigerate for about an hour, stirring the frosting after about 30 minutes. Don't let it chill too long before frosting your cake, though, because it gets quite firm, like a cream cheese tart filling. If that happens, just bring it to room temperature and then frost.
Refrigerate in an airtight container for up to 3 days and refrigerate anything you frost with this frosting. The frosting firms up once refrigerated so if you want the softer frosting texture (rather than a cream cheese tart filling kind of texture), let the cake or cupcakes come to room temperature before serving.