01 -
Pop your butter into the bowl of a stand mixer. Use the whisk attachment and mix on medium-high for about 3 minutes until it’s super soft and airy.
02 -
Pour in the vanilla extract.
03 -
Keep the mixer on low. Little by little, toss in the powdered sugar, milk, and salt. Don’t forget to scrape the sides and bottom of the bowl now and then.
04 -
Crank up the speed to medium-high (or high) and let it whip for at least 3 minutes—up to 7 if you’ve got the time.
05 -
Too thick to spread easily? Add some more milk, a bit at a time, and mix until it’s just right.
06 -
Tuck it into the fridge for up to 2 weeks. Before you use it, whip it up again to get it smooth.