1. Insert Butterfly. Mix on speed 4 until buttermilk splits from butter. This can take between 1 minute and 5 minutes.
2. Remove Butterfly. Strain buttermilk from butter and set aside buttermilk for other uses.
3. Add 300 grams (10.5 oz) cold water to mixing bowl. Wash 5 sec/speed 5, then strain again. Repeat washing and straining until liquid runs clear, or almost clear.
4. Press butter, using butter press if you have one. Store butter in refrigerator.