Take your room temperature butter and cream cheese and add to the kitchen aid. Mix until very creamy. Add ½ of the powdered sugar and mix on low. Add the rest of the powdered sugar, as well as the vanilla and milk. The frosting should be thick so do not add so much milk that it becomes runny. Once the cake cools, you can add the frosting. If you are not going to frost the cake right away, place the frosting into the refrigerator.
Recipe by Growing Weisser at https://www.growingweisser.com/carrot-cake-with-a-healthy-twist