Combine Greek yogurt, cream, sweetener, rosewater or vanilla, and a pinch of salt in the bowl of a stand mixer fitted with a whisk attachment.
Mix at low speed to start, then increase to high and whip until mixture is thick and stiff, about 5 minutes.
Use immediately as a soft, whipped cream–like topping, or, to serve as a parfait, divide into serving dishes and refrigerate until thickened (roughly to 45°F/7°C).
