Preheat oven to 425 degrees. Place bacon in a large skillet and fry over medium high heat until crisp. Drain on paper towels, then chop coarsely. Sprinkle bacon, cheese and onion onto pastry shell.

In a medium bowl whisk together eggs, cream, salt, sugar, and cayenne pepper. Pour mixture into pastry shell.

Bake 15 minutes in the preheated oven. Reduce heat to 300 degrees and bake an additional 30 minutes or until a knife inserted 1 inch from edge comes out clean. Allow quiche to sit 10 minutes before cutting into wedges.