With a handheld blender, whip the cream in a bowl until it comes to a peak.
Add in 6oz. of cream cheese and continue mixing until smooth and set aside.
In another bowl, mix in sweetener, raspberries, strawberries, lemon zest, and the remaining cream cheese and blend thoroughly until smooth.
Fill cups with whip cream, then add a layer of blueberries followed by raspberry puree. Repeat the process until layer fills up and top with blueberries.
Notes
Be sure to have a clean and dry bowl before you start whipping the heavy cream or it won't be able to double in size.