Whisk the cream with the sugar and vanilla until all the sugar has dissolved and the cream starts to thicken. Add the yoghurt, whisking it in to incorporate and then pour into a bowl or container that has a lid. Put the lid on and put in the freezer. After an hour give the mixture an energetic whisk with a hand whisk or electric mixer. Put it back in the freezer and then whisk again after another couple of hours. When the ice cream is nearly firm, give one last whisk and put it back in the freezer to set.
Alternatively, pour into your ice cream machine and churn, following the manufacturer’s instructions.