Measure 2 cups of heavy cream and ¼ cup of yogurt into each quart sized jar (or one 2 quart container if you have it), and mix until well combined. I usually lid the jars and shake them like a cocktail, then remove the lid.

Place a coffee filter or clean cloth over the jars and a rubber band to hold in place. Let sit at room temperature for 1-2 days. It should be thickened and smell slightly tangy and pleasantly sour.

Scoop and pour the cream into the bowl of a stand mixer and fit with whisk attachment. Cover the stand mixer with plastic wrap, or drape a kitchen towel over the mixer to catch splatter.

Whisk on high speed until the butter separates from the buttermilk. About 3-5 minutes. Watch out for splashing!

Set up the cheesecloth in a strainer in a large bowl. Pour the contents of the mixer bowl into the cheesecloth and strain off the buttermilk. Store the buttermilk in the fridge for another use.

Gather the ends of the cheesecloth and squeeze the last of the buttermilk out by twisting the cloth to tighten the ball of butter.

Place butter in a large bowl, and pour 1 cup of ice water over the butter. Using a wooden spoon, fold the butter in the ice water for about 30 seconds, washing the butter with the water. This will get difficult as the butter gets colder, but keep going! The ice water wash removes any buttermilk that is trapped in pockets inside the butter, which will prevent spoilage. Discard liquid after it has turned cloudy. Repeat twice more with 1 cup of ice water until the liquid is mostly clear.

Divide cultured butter into desired portions and wrap with parchment paper.