In a large bowl, beat the cream cheese and butter together on high speed until smooth and creamy, using either a handheld mixer or stand mixer fitted with a paddle or whisk attachment.
Add the powdered sweetener, pure vanilla, and sea salt (if using). Beat on low for 30 seconds, or until well combined.
Frosting can be stored in the refrigerator, tightly covered, for 5 days. Then, allow it to come to room temperature before using.
To freeze, place it in a ziplock baggie and push all of the air out. Seal, and store in the freezer for up to 3 months.