Beat your softened butter till smooth. Make sure that is has had time to soften, this is key to smooth icing.
Mix in 3 cups of powdered sugar a cup at a time, mixing well in between each cup.
Add Milk and dash of vanilla.
Separate the icing into different containers
Mix in colored food coloring.
On a flat bowl or plate with a lip, pour each icing color into different sections. Let them slightly run together.
Then grab your cookies, donuts or your favorite dessert and dip and twist slighting into the icing.
This creates a fun tie-dye effect!