Butter is easy to churn without any cultures. Just use your wisk on the mixer and let the heavy cream (40% butterfat is best) naturally seperate into butter and buttermilk. You then add whatever flavorings, salt, or herbs you want and squeeze the buttermilk out with your hands. When it is solidly compacted, rinse it with water and it will keep for up to 45 days at fridge temps- it freezes well if you can't use it all at once. I yield about 1.5lbs of butter from a half gallon of 40% cream.