Put the buttermilk in a quart jar then add the whole milk
Stir or shake the jar to mix well.
Put in a warm (70 - 77°F) place to culture for 12 to 18 hours.
After it has thickened, chill for 6 hours before using.
Notes
IF USING THE MOTHER CULTURE: Use 1 Tablespoon of mother culture to 1 cup of whole milk. Mix and let culture for 12 to 18 hours. Chill for 6 hours before using.