2 cups cream
3 tbsp buttermilk
Heat cream until just tepid (you just want to take the chill off it). Remove from heat and stir in buttermilk. Put in a lidded glass jar and leave to rest at room temperature for 24 hours, stirring a couple of times. Don’t worry about leaving the mixture out of the fridge, as the cultures in the buttermilk stop it from going off and will transform the mixture into Crème Fraîche.
After 24 hours at room temperature the mixture will have thickened somewhat. Stir or shake, cover again and put in the fridge for another 24 hours. It will continue to thicken a little and will develop the lovely light acidic flavour that defines Crème Fraîche. To thicken, simply shake in the jar or whip to your desired consistency. Crème Fraîche will keep in the fridge for up to 10 days.