Bake the unpricked pastry shell in a 450 degree F oven for 4 to 5 minutes or until it just begins to puff. Remove from oven. Reduce oven temperature to 375 degrees F.
Meanwhile, in a medium skillet, cook turkey and onion in butter over medium-high heat until onion is tender, but not brown. Sprinkle cheese over bottom of prebaked shell. Spoon turkey mixture over cheese.
In a medium bowl, whisk together the eggs, the cream, the mustard, the salt and the red pepper. Pour over the cheese-turkey mixture.
Bake in the 375 degree F oven for about 30 minutes or until a knife inserted near center comes out clean. If necessary, cover edge of crust with foil to prevent overbrowning. Let quiche cool for 10 minutes before serving.
