Fit the steel knife blade into the work bowl of your food processor. Process cream until whipped, about 30 seconds. Add water and ice cubes. Process 2-3 minutes until butter has formed and separated from the liquid. No harm will be done if you overwhip this mixture. Pour butter and liquid into a fine strainer. With a rubber spatula, gently press butter against sieve to remove excess moisture. Do Not press too hard or butter will go through strainer. Refrigerate butter in a covered container.

This makes 1/3 cup butter. If you prefer salted butter, add 1/8 teaspoon or less of salt to cream before processing.