In a large mixing bowl, combine 1 cup of slightly softened butter with 2-3 teaspoons of vanilla extract. Using a hand mixer or stand mixer, whip on medium speed for about 2 minutes, or until they're well blended.
Gradually add in the sifted powdered sugar, starting your mixer on low to avoid a sugar snowstorm in your kitchen. Once the sugar begins to incorporate, increase the speed to medium-high and continue mixing for another 30-45 seconds until the mixture is fluffy.
Check the texture of your frosting. If it's too thick or crumbly, add milk a teaspoon at a time, mixing well after each addition, until you reach a smooth consistency.
Give your frosting a little taste. If it needs a touch more vanilla to hit that sweet spot, go ahead and whisk in just a bit more. If the consistency is too thick, add a little more milk and mix again.