Measure out the butter, powdered sugar and vanilla into a large bowl or the bowl of a stand mixer.
Using a hand or stand mixer, start to combine the butter into the powdered sugar.
With the mixer on, slowly stream in your milk tablespoon by tablespoon until it starts to come together and look creamy.
If it hasn’t come together, add another tablespoon, mix and wait it out. After about 2 or 3 tablespoons, your frosting should be thick enough to hold its shape, but light enough to have a butter knife or rubber scraper run through it with ease.
Once you reach this point, you are done and the buttercream is ready to use.