In a pint sized mason jar add in your buttermilk and heavy cream.

Place a lid on the jar and shake well making sure to fully combine the buttermilk and cream.

Place on the counter and let it set for 12-24 hours. This all depends on the temperature of your house. The warmer it is the faster it will thicken.

After the creme fraiche has thickened place the jar in the fridge and store for up to 2 weeks.