In a large mixing bowl, with an electric mixer on medium speed, combine heavy cream, the remaining 1 tablespoon sugar substitute and the vanilla, beating to soft peaks. Add yogurt (1½ single serving containers) and beat to stiff peaks.
In four parfait glasses, alternate layers of the berry mixture, cream filling and crumbled Atkins bar, making at least two layers of each.
Top each with some of the remaining ½ cup strawberries and serve.