Place eggs in a large pot, and cover with cold water by 1 inch. Bring to a boil. Immediately remove from heat, and let stand, covered, for 13 minutes. Drain, and run under cold water to cool.
Peel eggs; slice a bit of the white off each short side so they can sit flat. Halve crosswise, and remove yolks. Mash yolks with creme fraiche, mustard, and lemon zest. Pass through a sieve. Stir in olives. Season with salt and pepper. Spoon or pipe yolk mixture into hollow of each egg white. Garnish each egg with an olive slice.
This is one of the six deviled egg recipes from this site that I made for christmas; the green olive was bad, the black olive was good. It may have been the brand of green olive that bought. There are thousands of different kinds of olives, I may try a different kind next time. Just goes to show you, don't skimp on price.