Cream together the cream cheese and sweetener with a hand mixer or stand mixer til smooth. If you're not using sweetener then whip cream cheese by itself til smooth.
Add cold heavy cream and half & half to the whipped cream cheese mixture. Whip all the ingredients until a smooth foam forms. This could take less than 5 minutes.
Pour iced coffee and any flavored syrup over ice. Top iced coffee with cream cheese foam.
Video
Notes
room temperature cream cheese works best because it whips up smoother faster
very cold cream and half & half works best because it foams faster
foam topping is good for 3 days in the fridge though it may deflate