If you have plenty of ice cubes, you can have the ice cream mixture ready for churning in less than one hour by cooling it in an ice bath. Note that the time and quantities of ice given below, are for an ice cream mixture that has been cooled down (it is not hot to the touch).
How to prepare an ice bath for fast chilling:
1. Put the ice cream mixture in a bowl made of heatproof glass or stainless steel; these materials help the mixture chill fast; and don’t break in sudden temperature changes. Avoid using a plastic bowl which will take forever to cool, or a regular glass bowl that may break upon contact with the ice bath.
2. Nest the bowl with the ice cream mixture into a large empty bowl (it should be large enough to fit ice cubes on the sides) and fill the sides of the large empty bowl with ice cubes. How many ice cubes? Well, the more ice you put in, the faster it will chill.
3. Pour cold water into the sides of the large bowl, taking care that no water slips into the ice cream mixture. Pour as much cold water as needed so that the level of the water bath in the large bowl is 2 cm / 1 inch above the ice cream mixture. Add more ice cubes to keep them plentiful in the water.
For this quantity of ice cream mixture, we started with approx. 500 g; 17 oz ice cubes and less than 1 litre fridge-cold water.
4. Refresh the ice bath with new ice cubes as soon as the older ones start to melt. If you have a thermometer, add enough ice cubes to keep the water well below 10° C / 50° F – take care that you measure the temperature of the water itself, not the ice temperature. The colder the ice bath, the faster the ice cream mixture will chill. You may need to remove water from the ice bath if it starts to overflow; to do so, carefully remove the bowl with the ice cream mixture, pour out the excess water and put the bowl back in. We used approximately 250 g; 9 oz additional ice cubes.
5. Stir often, leaving the spatula in the bowl during the cooling process. The ice cream mixture is ready for churning when it is fridge-cold to the touch (anywhere between 4-12° C / 39-54° F is perfectly ok).
6. Remove the bowl with the ice cream mixture from the ice bath, and wipe its bottom with a kitchen towel. The ice cream mixture is now ready for churning.