How to Make It
In a food processor, combine the flour, salt and baking powder; pulse to blend. Add the butter and pulse until it is in 1/2-inch chunks. Add the crème fraîche and pulse just until evenly moistened.
Transfer the soft crumbly mixture to a sheet of plastic wrap and press the crumbs together. Pat the pastry into 2 disks. Wrap and refrigerate until chilled.