• 1/2 cup (1 stick) unsalted butter , softened
• 1/2 vanilla bean , scraped
• 1/2 teaspoon salt
• 1/3 cup milk
• 4 cups confectioners' sugar (1 pound box), plus more if necessary

Cream the butter in a medium-size bowl until very smooth. Stir in the vanilla-bean seeds until they're evenly distributed. Add the salt and milk, and stir until combined. Sift the sugar over the butter mixture and stir the mixture until it's perfectly smooth. If the frosting is too loose, add a few more tablespoons of confectioners' sugar, and stir until smooth. Cover with plastic wrap until you're ready to use; mix well just before using.