Mix together the cream and maple syrup in a bowl or container that has a lid. Whisk in the milk and vanilla. Put the lid on the bowl and put it 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.