Remove the lid from the ice cream maker canister. Measure cream, half and half, sugar and vanilla and add to the ice cream maker canister and give it a good stir. Replace the lid and close. Return the canister to the ice cream maker.
Layer crushed ice and rock salt around the canister inside the ice cream maker.
Cover the entire ice cream maker with a towel so ice doesn't come out when cranking.
Crank for about 20-30 minutes until ice cream becomes solid and it becomes difficult to crank.