How To Make Crème Fraîche From Sour Cream (With Only One Extra Ingredient)

Crème fraîche is a dairy product made from cream soured with live bacteria culture. In fact, its name literally translates to "fresh cream." That simplicity means that you don't have to scour grocery stores for a container if you want fresh crème fraîche for your morning scrambled eggs. You can make your own almost instantly by combining sour cream and just one ingredient, heavy cream.

To make crème fraîche, simply combine about two cups of heavy cream with two tablespoons of sour cream (that's a 1:16 ratio), cover the mixture, and let it sit out at room temperature for at least 12 hours, then let it set in the fridge. Sour cream contains a bacteria culture just like crème fraîche, and when combined with heavy cream, it gives the mix the mildly sour, nutty taste that crème fraîche is known for (it should also prevent bacterial growth of anything bad, but please use common sense and discard anything that seems off). Some sources indicate that you can let it rest for longer than 12 hours to make it softer and thinner, or adjust the ratio of sour cream to affect the thickness and level of sourness. In a pinch, you can mix sour cream and heavy cream and use it right away, though it won't be quite the same.

Compared to the sour cream you'd add to your mashed potatoes, crème fraîche is thicker and milder, with more of a nutty flavor. It has more fat and less protein, so unlike sour cream, it typically doesn't curdle when you add it to hot or acidic foods. This makes crème fraîche a great thickener for many dishes, such as soups and casseroles.

Crème fraîche is made by adding a starter culture of bacteria to cream, which is then left in a controlled environment to allow the bacteria to ferment and multiply. This culture is mostly made up of lactic acid bacteria, which consumes lactose within the cream to create lactic acid, thickening the crème fraîche and giving it its signature tangy flavor.

This is why it's so easy to make crème fraîche using fermented dairy products like buttermilk or sour cream. They already have a lot of the same bacteria, so you're essentially replicating the same process that makes store-bought crème fraîche in your own home. Your homemade version won't taste exactly the same since the bacteria cultures are different, but it's still a lovely, versatile ingredient that complements a wide variety of other foods.

Everything depends on those specific bacteria cultures, so without them, the crème fraîche won't come out right. If you're trying to make it at home, never leave the heavy cream out without another fermented dairy product mixed in. Without the good bacteria to crowd it out, the bad bacteria inside will multiply instead and cause it to spoil.