Beat butter with an electric mixer until creamy. Sprinkle salt over butter and stir again to combine.
1 cup unsalted butter softened to room temperature, ¼ teaspoon salt
Gradually, about ½ cup at a time, add powdered sugar, waiting until each cup is completely mixed before adding more.
3 cups powdered sugar
With mixer on medium-low speed, add the heavy cream, one tablespoon at a time. Once ingredients are well incorporated, gradually increase speed to high and beat for about 30 seconds.
3 Tablespoons heavy cream
Add vanilla extract and stir well.
1 teaspoon vanilla extract
Pipe or spread frosting over cooled cupcakes. Top with sprinkles, if desired. This frosting will be fine at room temperature for 2 days or refrigerated in an airtight container for about a week.