1. Cream butter in the bowl of a stand mixer. Gradually add sifted sugar and vanilla. Add cream gradually until desired consistency is achieved. Beat until fluffy and smooth. (Add food coloring here, if using).
2. Spread onto cooled cookies or scoop into a piping bag and pipe onto cookies. (Add sprinkles here, if using).
Using cream or milk will change the consistency; cream will make thicker frosting, milk thinner. Add gradually until desired consistency is achieved.
If using a piping bag, frosting can be refrigerated a bit for easier piping.