In a large mixing bowl, use a hand or stand mixer fitted with a paddle or whisk attachment to cream the softened butter. Beat on medium-high speed for about 4–5 minutes, or until the butter is pale yellow and smooth. Scrape down the sides of the bowl as needed.

Turn off the mixer and add the powdered sugar and vanilla extract. Start mixing on low speed to avoid a sugar cloud. Once the mixture begins to incorporate and looks crumbly, increase to medium-high speed and whip for 3–4 minutes until light and fluffy.

Evaluate the texture of your frosting. If it's too thick, gradually mix in milk or cream, ½ tablespoon at a time, until it reaches your desired consistency—whether that's stiff for piping, or smooth for spreading.

Your frosting is now ready to use! Spread it over cakes or pipe onto cupcakes immediately. If not using right away, it can be stored in an airtight container at room temperature for up to 2 days or in the fridge for up to a week.