Don't worry about the creme fraiche spoiling while it's sitting on the counter; the acid in the mixture prevents bacterial disease associated with dairy products.
- 1 cup heavy cream
- 2 tablespoons buttermilk
In a bowl, combine the cream and buttermilk. Cover with a clean kitchen cloth in a warm, draft-free place and let sit until thickened, but still a pourable consistency, 12 to 16 hours. Stir and refrigerate until ready to use. (Can be refrigerated for up to 1 week.)