by Amanda Haas
Preheat oven to 375°F.
Pierce bottom and sides of pastry shell with a fork. Bake at 375°F for 15 minutes. Let cool on a wire rack. Increase oven temperature to 450°F.
Heat oil in a large nonstick skillet over medium-high heat. Add onion; sauté 8 minutes or until tender. Remove from pan; let cool.
Sprinkle onion, bacon, and cheese into pastry shell. Combine eggs and egg whites in a bowl, beating with a whisk. Add milk and remaining ingredients, beating with a whisk.
Pour milk mixture over cheese mixture in pastry shell. Place quiche on a baking sheet. Bake at 450°F for 10 minutes. Reduce oven temperature to 350°F. Bake at 350°F for 40 minutes, shielding after 15 minutes, if necessary, to prevent excess browning. Let cool on wire rack 15 minutes. Cut into wedges, and serve immediately.