Ferments Kitchen Basics

Cultured Butter

Butter — called “coagulated sunlight” by the poet Seamus Heaney — is one life’s great luxuries. By fermenting cream before churning it, we can produce butter with an incredible depth of flavor, plus a healthy dose of beneficial bacteria. 

Making butter is easy peasy, but it’s useful to understand the science behind the transformation taking place in your food processor. Butter is the solid fat that separates from cream when it has been churned or agitated. By agitating the cream (basically just jostling everything around a bunch), the membranes of the butterfat are ruptured, allowing the butterfat to stick together and form large fat globules.


  • food processor
  • mesh sieve
  • an incubator (Don’t be scared! This can be as simple as a thermos filled with warm water. See below for details)


  • heavy cream (the nicer the cream, the nicer the butter, so stick with local, pastured, or organic)
  • a small amount of yogurt
  • salt (optional, but you really should)


Culturing the Cream
  • Mix together a tablespoon of yogurt for every 2 pints of cream in a glass jar. Thoroughly mix and incubate for 6-24 hours. (See instructions below.) The cream will thicken a bit and taste pleasingly sour. Stick it in the fridge and allow to chill for at least 12 hours before churning.
  • In order for the cream to ferment, it must incubate at a steady temperature of 110 °F for 6-24 hours. There are several ways to do this. Here are a few:
    In an insulated cooler. Place container of cream in the cooler. Pour 110 °F water about 3/4 of the way up the jar. Close lid tightly and wrap the cooler in a blanket. Check every couple of hours, and replace the water if it gets too cool.
    In a slow cooker. Program a slow cooker to 110 °F. Place the container of cream inside. Wrap the slow cooker in a towel and let it incubate. Instant Pots also have an incubating function.
    In a gas oven with the pilot light lit. A gas oven, turned off but with the pilot light lit, maintains a temperature of approximately 110 °F. Also a fancy electric oven may be able to set the temperature to 110 °F.
Churning the Butter
  • Once cream is fully chilled, place in food processor and blend until the solid butter separates from the liquid buttermilk. The cream will go through several transformations, first rising and turning into whipped cream, and then sinking a bit and getting grainy, before fully separating into butter and buttermilk.
  • Place a mesh sieve over a bowl and pour in the contents of the food processor. The solid butter will remain in the sieve while the buttermilk will drain out into the bowl below.
    Over the sieve, knead the butter to remove as much liquid as possible. To do this, press a blob of butter between your flattened palms, fold butter in half, press again, repeat until little to no buttermilk weeps out. Repeat with remaining butter until everything looks smooth (like buttah!)
  • Mix in salt and other flavorings with the butter. Be sure to save buttermilk for cooking, baking (pancakes, biscuits, or DIY hair conditioner).


Don’t feel like fermenting the cream? Just use regular heavy cream and start at the churning the butter step. It won’t be quite as delicious, but it definitely works in a pinch!