In a medium bowl, cream the butter and cream cheese together with a mixer until fully combined.

Add the sweetener and vanilla extract and beat slowly until the sweetener is incorporated (going slowly will avoid the sweetener from getting blown into the air)

Once the sweetener is incorporated, beat on high for 1-2 minutes or until fluffy.

Use immediately, or store in an airtight container in the refrigerator for up to a week, or in the freezer for up to 3 months. Then bring to room temperature before using.