Ideally, stand cream cheese and butter at room temperature for half an hour to soften before proceeding.
Beat cream cheese with a handheld electric or stand mixer until it is smooth and creamy (about 1 minute on med-high speed).
Add butter and beat again until combined and smooth.
Sift in icing sugar and cocoa powder and beat on low-med speed until combined.
Add milk and beat again on low-med speed until combined.
Notes
Using:If you're going to add the icing with a spatula, you can just go ahead and use it immediately.If you'd like to pipe the chocolate cake cream cheese icing, place in the fridge for 15-30 minutes first to help the icing keep its shape better as you pipe it.Storing:Store leftover icing in an airtight container in the fridge for up to 5 days. Let soften out of the fridge for half an hour and stir vigorously with a wooden spoon before using.Freezing:Store leftover icing in an airtight container in the freezer for up to 3 months. To use again, thaw overnight in the fridge and then beat the frosting for about 5-10 seconds or until it's smooth and creamy.Nutrition:The nutrition information is an automatically generated estimate and is not guaranteed to be accurate.Tips:Ideally, stand cream cheese and butter at room temperature for half an hour to soften and then chop into cubes before beating.When beating in the dry ingredients, start off on the very lowest setting to ensure they combine with the cream cheese and butter rather than flying out of the bowl.