Add yogurt to heavy cream as a starter culture
Let the mixture sit at room temperature for 48 hours to culture
Chill the cultured cream in the refrigerator for a couple hours
Pour the chilled mixture into a Kitchen Aid mixer (or food processor/blender)
Mix until the mixture reaches the whipped cream phase
Continue mixing past the whipped cream phase until butter and buttermilk separate
Strain the butter using a fine sieve or honey strainer
Rinse the butter in very cold water multiple times to remove buttermilk
Store cultured butter in the refrigerator
Save the buttermilk for other uses
