Beat the softened butter with an electric mixer on medium speed until smooth and creamy, about 2 to 3 minutes.
Add the powdered sugar gradually, mixing on low speed after each addition to prevent a cloud of sugar.
Add the vanilla extract and salt. Mix until combined
Add 2 tablespoons of heavy cream or milk and beat until the buttercream becomes light and fluffy.
Beat the finished buttercream for another 1 to 2 minutes until smooth.
If desired, divide the frosting into bowls and tint with gel food coloring.
Transfer the buttercream to piping bags fitted with your preferred decorating tips, or use an offset spatula to frost and decorate your cake.