01 -
Whisk softened butter using a stand mixer with the whisk tool on medium-high for 3 minutes. It should look soft and airy.
02 -
Pour in the vanilla and mix briefly to combine.
03 -
Lower the mixer speed and slowly toss in powdered sugar, salt, and milk. Keep scraping the sides and bottom of the bowl as you go.
04 -
Turn the mixer up to medium-high or high and whip everything together for a minimum of three minutes. You can keep it going for up to seven minutes if you want extra fluffy frosting.
05 -
If it's too thick and hard to spread, mix in small amounts of extra milk until it's easier to work with.
06 -
Put in the fridge for up to 2 weeks. Make sure to whip again before using.