Crème Fraîche

Combine the ingredients

1. Mix the heavy cream and buttermilk (or yogurt) in a clean jar or bowl. Stir well to combine. The buttermilk or yogurt acts as the starter culture for the fermentation process.

Cover and let it sit

1. Cover the jar with a clean kitchen towel or lid, but don’t seal it completely airtight. The cream needs exposure to air for fermentation. Leave the mixture at room temperature (ideally around 70°F or 21°C) for 12 to 24 hours.

Check the consistency

1. After the resting period, the cream should have thickened and developed a tangy flavor. It will be smooth, creamy, and have a subtle sourness. If it's not thick enough, let it sit for a few more hours.

Refrigerate

1. Once it reaches the desired consistency, cover the jar with a lid and refrigerate. The crème fraîche will continue to thicken slightly as it chills. It should last for about 1 to 2 weeks in the refrigerator.