01 - In a large mixing bowl, beat the softened butter until light and creamy, about 2 minutes.
02 - Add powdered sugar gradually, 1 cup at a time, mixing well after each addition.
03 - Stir in molasses, milk, vanilla extract, salt, and all spices until combined.
04 - Beat on medium-high speed for 2 to 3 minutes until smooth and fluffy. If too thick, add additional milk, 1 teaspoon at a time, to reach desired consistency.
05 - Use immediately to frost cooled gingerbread cookies, cakes, or cupcakes. For piping, transfer to a piping bag fitted with a tip.