Dissolve the cornstarch in 50ml whole milk, leave to rest.
In a small saucepan over medium heat combine the heavy cream, the leftover milk, honey, a pinch of salt, a cinnamon stick, ground ginger, stir together, bring to an almost boil, take off heat, add the dried rooibos (or 3 good-quality rooibos tea bags), cover and let steep 10min. Sieve the mixture, discarding the tea bags and the cinnamon stick, return into the saucepan over medium heat, add the cornstarch milk and cook constantly stirring until thickened. Take off heat, add the cream cheese, stir until fully combined. Cool to room temperature, then transfer into the fridge overnight.
Freeze according to the manufacturer's instructions. Store in an airtight container or spoon right away.