In a mixing bowl, combine the powdered sugar, apple butter, vanilla extract, and ground cinnamon.

Mix on low speed until combined.

Gradually add milk, one tablespoon at a time, until the icing reaches your desired consistency.

If the icing is too thick, add more milk; if too thin, add more powdered sugar.

Once the icing is smooth and creamy, use it immediately to frost your favorite cakes or cupcakes.

If not using right away, cover the bowl with plastic wrap to prevent it from drying out.