In a medium saucepan combine half-and-half and sweetener. Cook, stirring frequently, over medium heat until sweetener is dissolved. Increase heat to medium-high to bring mixture to a boil. Cook, stirring occasionally and adjusting heat as needed to maintain a brisk simmer until mixture is thickened and turns offwhite, about 15 minutes. Transfer to a jar and refrigerate to chill.
In a medium saucepan combine water and sweetener. Bring to a boil over medium-high heat, stirring to dissolve sweetener. Take off heat and add rooibos, black tea, cardamom, star anise, and vanilla bean pod and seeds. Let steep for 20 minutes.
Strain tea to remove spices and vanilla pod. Cool tea completely.
To serve, fill a glass with ice and pour tea over ice. Top with 2 tablespoons condensed milk.