Creme fraiche substitutes include sour cream and even plain yogurt. If, however, you will be heating your “creme fraiche,” then making your own is a great and easy option. (Sour cream and yogurt tend to curdle when heated)

Creme Fraiche is fundamentally (in France anyway) non-pasteurized cream. The US equivalent is an artifically fermented cream which you can prepare yourself at home. Here’s a recipe:

Ingredients
1/2 cup sour cream
1/2 cup whipping cream
OR
1 cup whipping cream
3 tablespoons low-fat (not nonfat) buttermilk

Method
Mix your ingredients. Place in glass jar or non-reactive bowl. Cover and let stand 12 hours. After your cream has thickened and fermented, refrigerate and use within 10 days.