Whip the butter

• Place the room-temperature butter in a bowl.
• Beat on low to medium speed until lighter in color.
• Scrape down the sides of the bowl and the paddle to blend evenly.

Add salt and vanilla

• Add the salt and vanilla extract.
• Mix in slowly on low speed.

Mix in the sifted sugar

• Add the sifted powdered sugar gradually.
• Beat until smooth and fully combined.

Color and smooth

• Add food coloring if desired; a little blue dye neutralizes the butter's yellow tones for a cool white.
• Work out any air bubbles with a spatula in the bowl or in the piping bag.