In a large bowl, using a hand mixer or stand mixer, cream together the butter, shortening, and powdered sugar. This will take 3-5 minutes for the frosting to become creamy.
Add in the vanilla and 2 tablespoons of the heavy cream. Mix until well combined.
If using the frosting in a piping bag: If the consistency of the frosting is too thick to pipe add more cream 1 tablespoon at a time until the desired consistency has been reached.
If adding coloring to the frosting: add the food coloring now after the desired consistency of the frosting has been reached.
Fill a piping bag or scoop the frosting into a bowl to spread onto the cookies.
Best if used right away. Add sprinkles directly after frosting as the frosting will begin to harden.