Though cream is the ultimate cheater's ingredient in pastai regularly campaign against its inclusion in pasta carbonarasomehow crme frache is ok in my book. Like sour cream, it has that essential tang to temper the richness, yet it's lighter, sweeter, subtler. I can't imagine myself dolloping half a cup of sour cream into a bowl of pasta, but crme frache in this dish with fresh spring peas turns it into a decadent dinner.