Gather all the ingredients.

In a mixing bowl, add the softened unsalted butter and cream it using a mixer on medium speed for about 2 minutes until light and fluffy.

Slowly add the powdered sugar to the creamed butter, mixing it in gradually.

Pour in the milk and vanilla extract, mixing until smooth and well combined.

If the frosting is too thick, add more milk, one teaspoon at a time. If it's too thin, add more powdered sugar.

Mix on high speed for about 1 minute until the frosting is fluffy and light.

Taste the frosting and adjust the sweetness or vanilla extract if needed.

Use a spatula to frost your cooled cake or cupcakes.